XInput 2 support

XInput 2 support

[Po Lu]

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I hacked up support for handling XInput 2 events, though it hasn't
undergone any serious testing yet.

So the only advantage of this code over the existing Core Input code as
of present would be not relying on a fragile environment variable
(GDK_CORE_DEVICE_EVENTS) to work properly in GTK 3 builds.  Call me
paranoid, but this variable reeks of something that the GTK developers
will remove at some point in the future.  (AFAIK, it's already been
removed in GTK 4).

However, it paves the way for future support of high-resolution
scrollwheels, multi-touch trackpad support, and much more.

Would this support be worth installing?  Thanks.


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From 4e9a3ce0b548ea2d33f81d3b567f8dc1b64a127b Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 16 Oct 2021 13:15:36 +0800
Subject: [PATCH] Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables
(EMACS_CFLAGS): Add Xinput CFLAGS
(LIBES): Add XInput libs
* src/xfns.c (x_window): Set XInput 2 event mask
* src/xterm.c (x_detect_focus_change): Handle XInput 2 GenericEvents
(handle_one_xevent): Handle XInput 2 events
(x_term_init): Ask the server for XInput 2 support and set xkb_desc if
available
(x_delete_terminal): Free XKB kb desc if it exists
(init_xterm): Don't tell GTK to only use Core Input when built with
XInput 2 support
* src/xterm.h (struct x_display_info): Add fields for XKB and XI2
support
---
 configure.ac    |  22 ++
 src/Makefile.in |   7 +-
 src/xfns.c      |  56 ++++
 src/xterm.c     | 745 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h     |  14 +
 5 files changed, 839 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9ab0314428..0af8b65dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -485,6 +485,7 @@ AC_DEFUN
 OPTION_DEFAULT_ON([modules],[don't compile with dynamic modules support])
 OPTION_DEFAULT_ON([threads],[don't compile with elisp threading support])
 OPTION_DEFAULT_OFF([native-compilation],[compile with Emacs Lisp native compiler support])
+OPTION_DEFAULT_OFF([xinput2],[use version 2.0 the X Input Extension for input])
 
 AC_ARG_WITH([file-notification],[AS_HELP_STRING([--with-file-notification=LIB],
  [use a file notification library (LIB one of: yes, inotify, kqueue, gfile, w32, no)])],
@@ -4203,6 +4204,26 @@ AC_DEFUN
 AC_SUBST(XFIXES_CFLAGS)
 AC_SUBST(XFIXES_LIBS)
 
+## Use XInput 2.0 if available
+HAVE_XINPUT2=no
+if test "${HAVE_X11}" = "yes" && test "${with_xinput2}" != "no"; then
+   EMACS_CHECK_MODULES([XINPUT], [xi])
+   if test $HAVE_XINPUT = yes; then
+     # Now check for XInput2.h
+     AC_CHECK_HEADER(X11/extensions/XInput2.h,
+       [AC_CHECK_LIB(Xi, XIGrabButton, HAVE_XINPUT2=yes)])
+   fi
+   if test $HAVE_XINPUT2 = yes; then
+     AC_DEFINE(HAVE_XINPUT2, 1, [Define to 1 if the X Input Extension version 2.0 is present.])
+     if test "$USE_GTK_TOOLKIT" = "GTK2"; then
+       AC_MSG_WARN([You are building Emacs with GTK+ 2 and the X Input Extension version 2.
+This might lead to problems if your version of GTK+ is not built with support for XInput 2.])
+     fi
+   fi
+fi
+AC_SUBST(XINPUT_CFLAGS)
+AC_SUBST(XINPUT_LIBS)
+
 ### Use Xdbe (-lXdbe) if available
 HAVE_XDBE=no
 if test "${HAVE_X11}" = "yes"; then
@@ -5959,6 +5980,7 @@ AC_DEFUN
   Does Emacs support legacy unexec dumping?               ${with_unexec}
   Which dumping strategy does Emacs use?                  ${with_dumping}
   Does Emacs have native lisp compiler?                   ${HAVE_NATIVE_COMP}
+  Does Emacs use version 2 of the the X Input Extension?  ${HAVE_XINPUT2}
 "])
 
 if test -n "${EMACSDATA}"; then
diff --git a/src/Makefile.in b/src/Makefile.in
index 6d75e3537a..2b3e1f37e0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -256,6 +256,9 @@ XINERAMA_CFLAGS =
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -372,7 +375,7 @@ EMACS_CFLAGS=
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -522,7 +525,7 @@ LIBES =
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca..4fef8005a0 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ Copyright (C) 1989, 1992-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -3074,6 +3078,32 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3284,32 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
diff --git a/src/xterm.c b/src/xterm.c
index 961c61c245..3c30b328e8 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ Copyright (C) 1989, 1993-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ #define XtNinitialState "initialState"
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
 			      const XEvent *, int *,
 			      struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+			      XEvent *, int *,
+			      struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -4768,6 +4778,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+	if (!((xi_event->evtype == XI_Enter
+	       || xi_event->evtype == XI_Leave)
+	      && (focus_state & FOCUS_EXPLICIT)))
+	  x_focus_changed ((xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_FocusIn
+			    ? FocusIn : FocusOut),
+			   (xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_Leave
+			    ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+			   dpyinfo, frame, bufp);
+	break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7872,7 +7905,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
 		   const XEvent *event,
+#else
+		   XEvent *event,
+#endif
 		   int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -7898,7 +7935,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -9343,6 +9387,665 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	if (!dpyinfo->supports_xi2)
+	  goto OTHER;
+	if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+	  /* Not an XI2 event. */
+	  goto OTHER;
+	bool must_free_data = false;
+	XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+	/* Sometimes the event is already claimed by GTK, which
+	   will free its data in due course. */
+	if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+	  {
+	    must_free_data = true;
+	    xi_event = (XIEvent *) event->xcookie.data;
+	  }
+
+	XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+	XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+	XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+	XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+	XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+
+	/* A fake XMotionEvent for x_note_mouse_movement. */
+	XMotionEvent ev;
+	/* A fake XButtonEvent for x_construct_mouse_click. */
+	XButtonEvent bv;
+
+	if (!xi_event)
+	  {
+	    eassert (!must_free_data);
+	    goto OTHER;
+	  }
+
+	switch (event->xcookie.evtype)
+	  {
+	  case XI_FocusIn:
+	    any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+	    /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+	       minimized/iconified windows; thus, for those WMs we won't get
+	       a MapNotify when unminimizing/deconifying.  Check here if we
+	       are deiconizing a window (Bug42655).
+
+	       But don't do that on GTK since it may cause a plain invisible
+	       frame get reported as iconified, compare
+	       https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+	       That is fixed above but bites us here again.  */
+	    f = any;
+	    if (f && FRAME_ICONIFIED_P (f))
+	      {
+		SET_FRAME_VISIBLE (f, 1);
+		SET_FRAME_ICONIFIED (f, false);
+		f->output_data.x->has_been_visible = true;
+		inev.ie.kind = DEICONIFY_EVENT;
+		XSETFRAME (inev.ie.frame_or_window, f);
+	      }
+#endif /* USE_GTK */
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_FocusOut:
+	    any = x_any_window_to_frame (dpyinfo, focusout->event);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_Enter:
+	    any = x_any_window_to_frame (dpyinfo, enter->event);
+	    ev.x = lrint (enter->event_x);
+	    ev.y = lrint (enter->event_y);
+	    ev.window = leave->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    f = any;
+
+	    if (f && x_mouse_click_focus_ignore_position)
+	      ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+	    /* EnterNotify counts as mouse movement,
+	       so update things that depend on mouse position.  */
+	    if (f && !f->output_data.x->hourglass_p)
+	      x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+	    /* We may get an EnterNotify on the buttons in the toolbar.  In that
+	       case we moved out of any highlighted area and need to note this.  */
+	    if (!f && dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Leave:
+	    ev.x = lrint (leave->event_x);
+	    ev.y = lrint (leave->event_y);
+	    ev.window = leave->event;
+	    any = x_any_window_to_frame (dpyinfo, leave->event);
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+
+	    f = x_top_window_to_frame (dpyinfo, leave->event);
+	    if (f)
+	      {
+		if (f == hlinfo->mouse_face_mouse_frame)
+		  {
+		    /* If we move outside the frame, then we're
+		       certainly no longer on any text in the frame.  */
+		    clear_mouse_face (hlinfo);
+		    hlinfo->mouse_face_mouse_frame = 0;
+		  }
+
+		/* Generate a nil HELP_EVENT to cancel a help-echo.
+		   Do it only if there's something to cancel.
+		   Otherwise, the startup message is cleared when
+		   the mouse leaves the frame.  */
+		if (any_help_event_p)
+		  do_help = -1;
+	      }
+#ifdef USE_GTK
+	    /* See comment in EnterNotify above */
+	    else if (dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Motion:
+	    ev.x = lrint (xev->event_x);
+	    ev.y = lrint (xev->event_y);
+	    ev.window = xev->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    previous_help_echo_string = help_echo_string;
+	    help_echo_string = Qnil;
+
+	    if (hlinfo->mouse_face_hidden)
+	      {
+		hlinfo->mouse_face_hidden = false;
+		clear_mouse_face (hlinfo);
+	      }
+
+	    f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+	    if (f && xg_event_is_for_scrollbar (f, event))
+	      f = 0;
+#endif
+	    if (f)
+	      {
+		/* Maybe generate a SELECT_WINDOW_EVENT for
+		   `mouse-autoselect-window' but don't let popup menus
+		   interfere with this (Bug#1261).  */
+		if (!NILP (Vmouse_autoselect_window)
+		    && !popup_activated ()
+		    /* Don't switch if we're currently in the minibuffer.
+		       This tries to work around problems where the
+		       minibuffer gets unselected unexpectedly, and where
+		       you then have to move your mouse all the way down to
+		       the minibuffer to select it.  */
+		    && !MINI_WINDOW_P (XWINDOW (selected_window))
+		    /* With `focus-follows-mouse' non-nil create an event
+		       also when the target window is on another frame.  */
+		    && (f == XFRAME (selected_frame)
+			|| !NILP (focus_follows_mouse)))
+		  {
+		    static Lisp_Object last_mouse_window;
+		    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+		    /* A window will be autoselected only when it is not
+		       selected now and the last mouse movement event was
+		       not in it.  The remainder of the code is a bit vague
+		       wrt what a "window" is.  For immediate autoselection,
+		       the window is usually the entire window but for GTK
+		       where the scroll bars don't count.  For delayed
+		       autoselection the window is usually the window's text
+		       area including the margins.  */
+		    if (WINDOWP (window)
+			&& !EQ (window, last_mouse_window)
+			&& !EQ (window, selected_window))
+		      {
+			inev.ie.kind = SELECT_WINDOW_EVENT;
+			inev.ie.frame_or_window = window;
+		      }
+
+		    /* Remember the last window where we saw the mouse.  */
+		    last_mouse_window = window;
+		  }
+
+		if (!x_note_mouse_movement (f, &ev))
+		  help_echo_string = previous_help_echo_string;
+	      }
+	    else
+	      {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+		struct scroll_bar *bar
+		  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+		if (bar)
+		  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+		/* If we move outside the frame, then we're
+		   certainly no longer on any text in the frame.  */
+		clear_mouse_face (hlinfo);
+	      }
+
+	    /* If the contents of the global variable help_echo_string
+	       has changed, generate a HELP_EVENT.  */
+	    if (!NILP (help_echo_string)
+		|| !NILP (previous_help_echo_string))
+	      do_help = 1;
+	    goto XI_OTHER;
+	  case XI_ButtonRelease:
+	  case XI_ButtonPress:
+	    {
+	      /* If we decide we want to generate an event to be seen
+		 by the rest of Emacs, we put it here.  */
+	      Lisp_Object tab_bar_arg = Qnil;
+	      bool tab_bar_p = false;
+	      bool tool_bar_p = false;
+
+	      bv.button = xev->detail;
+	      bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+	      bv.x = lrint (xev->event_x);
+	      bv.y = lrint (xev->event_y);
+	      bv.window = xev->event;
+	      bv.state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+
+	      memset (&compose_status, 0, sizeof (compose_status));
+	      dpyinfo->last_mouse_glyph_frame = NULL;
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+
+	      f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+	      if (f && xev->evtype == XI_ButtonPress
+		  && !popup_activated ()
+		  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+		  && !FRAME_NO_ACCEPT_FOCUS (f))
+		{
+		  /* When clicking into a child frame or when clicking
+		     into a parent frame with the child frame selected and
+		     `no-accept-focus' is not set, select the clicked
+		     frame.  */
+		  struct frame *hf = dpyinfo->highlight_frame;
+
+		  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+		    {
+		      block_input ();
+		      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+				      RevertToParent, CurrentTime);
+		      if (FRAME_PARENT_FRAME (f))
+			XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+		      unblock_input ();
+		    }
+		}
+
+#ifdef USE_GTK
+	      if (f && xg_event_is_for_scrollbar (f, event))
+		f = 0;
+#endif
+
+	      if (f)
+		{
+		  /* Is this in the tab-bar?  */
+		  if (WINDOWP (f->tab_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tab_bar_p = EQ (window, f->tab_bar_window);
+
+		      if (tab_bar_p)
+			tab_bar_arg = handle_tab_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+
+#if ! defined (USE_GTK)
+		  /* Is this in the tool-bar?  */
+		  if (WINDOWP (f->tool_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tool_bar_p = EQ (window, f->tool_bar_window);
+
+		      if (tool_bar_p && xev->detail < 4)
+			handle_tool_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+#endif /* !USE_GTK */
+
+		  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+		    if (! popup_activated ())
+#endif
+		      {
+			if (ignore_next_mouse_click_timeout)
+			  {
+			    if (xev->evtype == XI_ButtonPress
+				&& xev->time > ignore_next_mouse_click_timeout)
+			      {
+				ignore_next_mouse_click_timeout = 0;
+				x_construct_mouse_click (&inev.ie, &bv, f);
+			      }
+			    if (xev->evtype == XI_ButtonRelease)
+			      ignore_next_mouse_click_timeout = 0;
+			  }
+			else
+			  x_construct_mouse_click (&inev.ie, &bv, f);
+
+			if (!NILP (tab_bar_arg))
+			  inev.ie.arg = tab_bar_arg;
+		      }
+		  if (FRAME_X_EMBEDDED_P (f))
+		    xembed_send_message (f, xev->time,
+					 XEMBED_REQUEST_FOCUS, 0, 0, 0);
+		}
+
+	      if (xev->evtype == XI_ButtonPress)
+		{
+		  dpyinfo->grabbed |= (1 << xev->detail);
+		  dpyinfo->last_mouse_frame = f;
+		  if (f && !tab_bar_p)
+		    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+		  if (f && !tool_bar_p)
+		    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+		}
+	      else
+		dpyinfo->grabbed &= ~(1 << xev->detail);
+
+	      if (f)
+		f->mouse_moved = false;
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyPress:
+	    {
+	      int state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+	      Lisp_Object c;
+#ifdef HAVE_XKB
+	      unsigned int mods_rtrn;
+#endif
+	      int keycode = xev->detail;
+	      KeySym keysym;
+	      char copy_buffer[81];
+	      char *copy_bufptr = copy_buffer;
+	      unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+	      int copy_bufsiz = sizeof (copy_buffer);
+#endif
+	      ptrdiff_t i;
+	      int nchars, len;
+
+#ifdef HAVE_XKB
+	      if (dpyinfo->xkb_desc)
+		{
+		  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+					    state, &mods_rtrn, &keysym))
+		    goto XI_OTHER;
+		}
+	      else
+		{
+#endif
+		  int keysyms_per_keycode_return;
+		  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+						      &keysyms_per_keycode_return);
+		  if (!(keysym = ksms[0]))
+		    {
+		      XFree (ksms);
+		      goto XI_OTHER;
+		    }
+		  XFree (ksms);
+#ifdef HAVE_XKB
+		}
+#endif
+
+	      if (keysym == NoSymbol)
+		goto XI_OTHER;
+
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+	      ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+	      /* Dispatch XI_KeyPress events when in menu.  */
+	      if (popup_activated ())
+		goto XI_OTHER;
+#endif
+
+	      f = x_any_window_to_frame (dpyinfo, xev->event);
+
+	      /* If mouse-highlight is an integer, input clears out
+		 mouse highlighting.  */
+	      if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+		  && (f == 0
+#if ! defined (USE_GTK)
+		      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+		      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+		  )
+		{
+		  clear_mouse_face (hlinfo);
+		  hlinfo->mouse_face_hidden = true;
+		}
+
+	      if (f != 0)
+		{
+		  /* If not using XIM/XIC, and a compose sequence is in progress,
+		     we break here.  Otherwise, chars_matched is always 0.  */
+		  if (compose_status.chars_matched > 0 && nbytes == 0)
+		    break;
+
+		  memset (&compose_status, 0, sizeof (compose_status));
+
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  inev.ie.modifiers
+		    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+		  inev.ie.timestamp = xev->time;
+
+		  /* First deal with keysyms which have defined
+		     translations to characters.  */
+		  if (keysym >= 32 && keysym < 128)
+		    /* Avoid explicitly decoding each ASCII character.  */
+		    {
+		      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+
+		      goto xi_done_keysym;
+		    }
+
+		  /* Keysyms directly mapped to Unicode characters.  */
+		  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+		    {
+		      if (keysym < 0x01000080)
+			inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      else
+			inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym & 0xFFFFFF;
+		      goto xi_done_keysym;
+		    }
+
+		  /* Now non-ASCII.  */
+		  if (HASH_TABLE_P (Vx_keysym_table)
+		      && (c = Fgethash (make_fixnum (keysym),
+					Vx_keysym_table,
+					Qnil),
+			  FIXNATP (c)))
+		    {
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = XFIXNAT (c);
+		      goto xi_done_keysym;
+		    }
+
+		  /* Random non-modifier sorts of keysyms.  */
+		  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+		       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+		       || (keysym >= XK_ISO_Left_Tab
+			   && keysym <= XK_ISO_Enter)
+#endif
+		       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+		       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+		       /* This recognizes the "extended function
+			  keys".  It seems there's no cleaner way.
+			  Test IsModifierKey to avoid handling
+			  mode_switch incorrectly.  */
+		       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+		       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+		       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+		       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+		       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+		       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+		       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+		       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+		       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+		       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+		       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+		       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+		       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+		       || keysym == XK_dead_abovedot
+#endif
+		       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+		       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+		       /* Any "vendor-specific" key is ok.  */
+		       || (keysym & (1 << 28))
+		       || (keysym != NoSymbol && nbytes == 0))
+		      && ! (IsModifierKey (keysym)
+			    /* The symbols from XK_ISO_Lock
+			       to XK_ISO_Last_Group_Lock
+			       don't have real modifiers but
+			       should be treated similarly to
+			       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+			    || (XK_ISO_Lock <= keysym
+				&& keysym <= XK_ISO_Last_Group_Lock)
+#endif
+			    ))
+		    {
+		      STORE_KEYSYM_FOR_DEBUG (keysym);
+		      /* make_lispy_event will convert this to a symbolic
+			 key.  */
+		      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+		      goto xi_done_keysym;
+		    }
+
+#ifdef HAVE_XKB
+		  int overflow = 0;
+		  KeySym sym = keysym;
+
+		  if (dpyinfo->xkb_desc)
+		    {
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz, &overflow)))
+			goto XI_OTHER;
+		    }
+		  else
+#else
+		    {
+		      block_input ();
+		      char *str = XKeysymToString (keysym);
+		      if (!str)
+			{
+			  unblock_input ();
+			  goto XI_OTHER;
+			}
+		      nbytes = strlen (str) + 1;
+		      copy_bufptr = alloca (nbytes);
+		      strcpy (copy_bufptr, str);
+		      unblock_input ();
+		    }
+#endif
+#ifdef HAVE_XKB
+		  if (overflow)
+		    {
+		      overflow = 0;
+		      copy_bufptr = alloca (copy_bufsiz + overflow);
+		      keysym = sym;
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz + overflow, &overflow)))
+			goto XI_OTHER;
+
+		      if (overflow)
+			goto XI_OTHER;
+		    }
+#endif
+
+		  for (i = 0, nchars = 0; i < nbytes; i++)
+		    {
+		      if (ASCII_CHAR_P (copy_bufptr[i]))
+			nchars++;
+		      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+		    }
+
+		  if (nchars < nbytes)
+		    {
+		      /* Decode the input data.  */
+
+		      setup_coding_system (Vlocale_coding_system, &coding);
+		      coding.src_multibyte = false;
+		      coding.dst_multibyte = true;
+		      /* The input is converted to events, thus we can't
+			 handle composition.  Anyway, there's no XIM that
+			 gives us composition information.  */
+		      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+		      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+				    nbytes);
+		      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+		      coding.mode |= CODING_MODE_LAST_BLOCK;
+		      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr, nbytes, Qnil);
+		      nbytes = coding.produced;
+		      nchars = coding.produced_char;
+		      copy_bufptr = (char *) coding.destination;
+		    }
+
+		  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+		  /* Convert the input data to a sequence of
+		     character events.  */
+		  for (i = 0; i < nbytes; i += len)
+		    {
+		      int ch;
+		      if (nchars == nbytes)
+			ch = copy_ubufptr[i], len = 1;
+		      else
+			ch = string_char_and_length (copy_ubufptr + i, &len);
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = ch;
+		      kbd_buffer_store_buffered_event (&inev, hold_quit);
+		    }
+
+		  inev.ie.kind = NO_EVENT;
+		  goto xi_done_keysym;
+		}
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyRelease:
+	    x_display_set_last_user_time (dpyinfo, xev->time);
+	    goto XI_OTHER;
+	  case XI_PropertyEvent:
+
+	  default:
+	    goto XI_OTHER;
+	  }
+      xi_done_keysym:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto done_keysym;
+      XI_OTHER:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13013,6 +13716,35 @@ #define NUM_ARGV 10
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+		       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+	dpyinfo->supports_xi2 = true;
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+				 XkbAllComponentsMask,
+				 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13445,6 +14177,10 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+	XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13604,9 +14340,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index de6ea50385..6d5f28c76e 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ #define XSync(d, b) do { gdk_window_process_all_updates (); \
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -474,6 +478,16 @@ #define MAX_CLIP_RECTS 2
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
-- 
2.31.1


[-- Attachment #3: Type: text/plain, Size: 117 bytes --]


(To test, configure with --with-xinput2 and make sure the XInput 2
development files are present on your computer.)

Re: XInput 2 support

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Date: Sat, 16 Oct 2021 13:37:13 +0800
> 
> I hacked up support for handling XInput 2 events, though it hasn't
> undergone any serious testing yet.

Thanks.  Would people who have this installed try the patch and report
what they see?

> So the only advantage of this code over the existing Core Input code as
> of present would be not relying on a fragile environment variable
> (GDK_CORE_DEVICE_EVENTS) to work properly in GTK 3 builds.  Call me
> paranoid, but this variable reeks of something that the GTK developers
> will remove at some point in the future.  (AFAIK, it's already been
> removed in GTK 4).

Who or what will promise us that XInput 2 will not be removed by those
same developers?

> However, it paves the way for future support of high-resolution
> scrollwheels, multi-touch trackpad support, and much more.
> 
> Would this support be worth installing?  Thanks.

Much of the code seems to be just a copy of the existing code in
xterm.c, just with different events.  Would it be possible to
preprocess XInput 2 events into X events, and then call the existing
code, instead of copy/paste-ing it?

Also, do these changes have any effect on user-visible behavior, or on
how users must set up their systems or how they use Emacs?  If so,
there should be suitable changes to the documentation.

Re: XInput 2 support

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> Who or what will promise us that XInput 2 will not be removed by those
> same developers?

XInput 2 is currently the standard modern input handling extension on
X-Windows, and GTK uses it to provide input features such as smooth
scrolling and touchscreen support on X-Windows whenever available.  The
legacy Core Input code is not as well maintained, and is missing certain
features.

> Much of the code seems to be just a copy of the existing code in
> xterm.c, just with different events.  Would it be possible to
> preprocess XInput 2 events into X events, and then call the existing
> code, instead of copy/paste-ing it?

I've already done that where possible (see the variables `ev' and `bv'
under "case GenericEvent:").  Everywhere else, I'm not comfortable with
preprocessing these XI events into X events.

> Also, do these changes have any effect on user-visible behavior, or on
> how users must set up their systems or how they use Emacs?  If so,
> there should be suitable changes to the documentation.

None at all.  The code falls back to Core Input if the X Server does not
have XInput2 installed, and the behaviour is identical when using both.
Thanks.

Re: XInput 2 support

[Po Lu]

Po Lu <luangruo@yahoo.com> writes:

> None at all.  The code falls back to Core Input if the X Server does not
> have XInput2 installed, and the behaviour is identical when using both.
                                                         ^^^^^^^^^^
Here, I meant to say "under".

Re: XInput 2 support

[Po Lu]

[-- Attachment #1: Type: text/plain, Size: 268 bytes --]

Po Lu <luangruo@yahoo.com> writes:

> (To test, configure with --with-xinput2 and make sure the XInput 2
> development files are present on your computer.)

Okay, I asked someone to test and he reported a problem with the menu
bar.  This updated patch should fix it.


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-Add-support-for-event-processing-via-XInput-2.patch --]
[-- Type: text/x-patch, Size: 33152 bytes --]

From e6b7ff3535dd91880079e3a2d8a10e6fdf7a9524 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 16 Oct 2021 13:15:36 +0800
Subject: [PATCH] Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables
(EMACS_CFLAGS): Add Xinput CFLAGS
(LIBES): Add XInput libs
* src/xfns.c (x_window): Set XInput 2 event mask
* src/xterm.c (x_detect_focus_change): Handle XInput 2 GenericEvents
(handle_one_xevent): Handle XInput 2 events
(x_term_init): Ask the server for XInput 2 support and set xkb_desc if
available
(x_delete_terminal): Free XKB kb desc if it exists
(init_xterm): Don't tell GTK to only use Core Input when built with
XInput 2 support
* src/xterm.h (struct x_display_info): Add fields for XKB and XI2
support
---
 configure.ac    |  22 ++
 src/Makefile.in |   7 +-
 src/xfns.c      |  56 ++++
 src/xterm.c     | 771 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h     |  14 +
 5 files changed, 865 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9ab0314428..0af8b65dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -485,6 +485,7 @@ AC_DEFUN
 OPTION_DEFAULT_ON([modules],[don't compile with dynamic modules support])
 OPTION_DEFAULT_ON([threads],[don't compile with elisp threading support])
 OPTION_DEFAULT_OFF([native-compilation],[compile with Emacs Lisp native compiler support])
+OPTION_DEFAULT_OFF([xinput2],[use version 2.0 the X Input Extension for input])
 
 AC_ARG_WITH([file-notification],[AS_HELP_STRING([--with-file-notification=LIB],
  [use a file notification library (LIB one of: yes, inotify, kqueue, gfile, w32, no)])],
@@ -4203,6 +4204,26 @@ AC_DEFUN
 AC_SUBST(XFIXES_CFLAGS)
 AC_SUBST(XFIXES_LIBS)
 
+## Use XInput 2.0 if available
+HAVE_XINPUT2=no
+if test "${HAVE_X11}" = "yes" && test "${with_xinput2}" != "no"; then
+   EMACS_CHECK_MODULES([XINPUT], [xi])
+   if test $HAVE_XINPUT = yes; then
+     # Now check for XInput2.h
+     AC_CHECK_HEADER(X11/extensions/XInput2.h,
+       [AC_CHECK_LIB(Xi, XIGrabButton, HAVE_XINPUT2=yes)])
+   fi
+   if test $HAVE_XINPUT2 = yes; then
+     AC_DEFINE(HAVE_XINPUT2, 1, [Define to 1 if the X Input Extension version 2.0 is present.])
+     if test "$USE_GTK_TOOLKIT" = "GTK2"; then
+       AC_MSG_WARN([You are building Emacs with GTK+ 2 and the X Input Extension version 2.
+This might lead to problems if your version of GTK+ is not built with support for XInput 2.])
+     fi
+   fi
+fi
+AC_SUBST(XINPUT_CFLAGS)
+AC_SUBST(XINPUT_LIBS)
+
 ### Use Xdbe (-lXdbe) if available
 HAVE_XDBE=no
 if test "${HAVE_X11}" = "yes"; then
@@ -5959,6 +5980,7 @@ AC_DEFUN
   Does Emacs support legacy unexec dumping?               ${with_unexec}
   Which dumping strategy does Emacs use?                  ${with_dumping}
   Does Emacs have native lisp compiler?                   ${HAVE_NATIVE_COMP}
+  Does Emacs use version 2 of the the X Input Extension?  ${HAVE_XINPUT2}
 "])
 
 if test -n "${EMACSDATA}"; then
diff --git a/src/Makefile.in b/src/Makefile.in
index 6d75e3537a..2b3e1f37e0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -256,6 +256,9 @@ XINERAMA_CFLAGS =
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -372,7 +375,7 @@ EMACS_CFLAGS=
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -522,7 +525,7 @@ LIBES =
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca..4fef8005a0 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ Copyright (C) 1989, 1992-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -3074,6 +3078,32 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3284,32 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
diff --git a/src/xterm.c b/src/xterm.c
index 961c61c245..e88e882487 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ Copyright (C) 1989, 1993-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ #define XtNinitialState "initialState"
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
 			      const XEvent *, int *,
 			      struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+			      XEvent *, int *,
+			      struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -4768,6 +4778,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+	if (!((xi_event->evtype == XI_Enter
+	       || xi_event->evtype == XI_Leave)
+	      && (focus_state & FOCUS_EXPLICIT)))
+	  x_focus_changed ((xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_FocusIn
+			    ? FocusIn : FocusOut),
+			   (xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_Leave
+			    ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+			   dpyinfo, frame, bufp);
+	break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7872,7 +7905,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
 		   const XEvent *event,
+#else
+		   XEvent *event,
+#endif
 		   int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -7898,7 +7935,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -9343,6 +9387,691 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	if (!dpyinfo->supports_xi2)
+	  goto OTHER;
+	if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+	  /* Not an XI2 event. */
+	  goto OTHER;
+	bool must_free_data = false;
+	XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+	/* Sometimes the event is already claimed by GTK, which
+	   will free its data in due course. */
+	if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+	  {
+	    must_free_data = true;
+	    xi_event = (XIEvent *) event->xcookie.data;
+	  }
+
+	XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+	XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+	XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+	XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+	XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+
+	/* A fake XMotionEvent for x_note_mouse_movement. */
+	XMotionEvent ev;
+	/* A fake XButtonEvent for x_construct_mouse_click. */
+	XButtonEvent bv;
+
+	if (!xi_event)
+	  {
+	    eassert (!must_free_data);
+	    goto OTHER;
+	  }
+
+	switch (event->xcookie.evtype)
+	  {
+	  case XI_FocusIn:
+	    any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+	    /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+	       minimized/iconified windows; thus, for those WMs we won't get
+	       a MapNotify when unminimizing/deconifying.  Check here if we
+	       are deiconizing a window (Bug42655).
+
+	       But don't do that on GTK since it may cause a plain invisible
+	       frame get reported as iconified, compare
+	       https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+	       That is fixed above but bites us here again.  */
+	    f = any;
+	    if (f && FRAME_ICONIFIED_P (f))
+	      {
+		SET_FRAME_VISIBLE (f, 1);
+		SET_FRAME_ICONIFIED (f, false);
+		f->output_data.x->has_been_visible = true;
+		inev.ie.kind = DEICONIFY_EVENT;
+		XSETFRAME (inev.ie.frame_or_window, f);
+	      }
+#endif /* USE_GTK */
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_FocusOut:
+	    any = x_any_window_to_frame (dpyinfo, focusout->event);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_Enter:
+	    any = x_any_window_to_frame (dpyinfo, enter->event);
+	    ev.x = lrint (enter->event_x);
+	    ev.y = lrint (enter->event_y);
+	    ev.window = leave->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    f = any;
+
+	    if (f && x_mouse_click_focus_ignore_position)
+	      ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+	    /* EnterNotify counts as mouse movement,
+	       so update things that depend on mouse position.  */
+	    if (f && !f->output_data.x->hourglass_p)
+	      x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+	    /* We may get an EnterNotify on the buttons in the toolbar.  In that
+	       case we moved out of any highlighted area and need to note this.  */
+	    if (!f && dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Leave:
+	    ev.x = lrint (leave->event_x);
+	    ev.y = lrint (leave->event_y);
+	    ev.window = leave->event;
+	    any = x_any_window_to_frame (dpyinfo, leave->event);
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+
+	    f = x_top_window_to_frame (dpyinfo, leave->event);
+	    if (f)
+	      {
+		if (f == hlinfo->mouse_face_mouse_frame)
+		  {
+		    /* If we move outside the frame, then we're
+		       certainly no longer on any text in the frame.  */
+		    clear_mouse_face (hlinfo);
+		    hlinfo->mouse_face_mouse_frame = 0;
+		  }
+
+		/* Generate a nil HELP_EVENT to cancel a help-echo.
+		   Do it only if there's something to cancel.
+		   Otherwise, the startup message is cleared when
+		   the mouse leaves the frame.  */
+		if (any_help_event_p)
+		  do_help = -1;
+	      }
+#ifdef USE_GTK
+	    /* See comment in EnterNotify above */
+	    else if (dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Motion:
+	    ev.x = lrint (xev->event_x);
+	    ev.y = lrint (xev->event_y);
+	    ev.window = xev->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    previous_help_echo_string = help_echo_string;
+	    help_echo_string = Qnil;
+
+	    if (hlinfo->mouse_face_hidden)
+	      {
+		hlinfo->mouse_face_hidden = false;
+		clear_mouse_face (hlinfo);
+	      }
+
+	    f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+	    if (f && xg_event_is_for_scrollbar (f, event))
+	      f = 0;
+#endif
+	    if (f)
+	      {
+		/* Maybe generate a SELECT_WINDOW_EVENT for
+		   `mouse-autoselect-window' but don't let popup menus
+		   interfere with this (Bug#1261).  */
+		if (!NILP (Vmouse_autoselect_window)
+		    && !popup_activated ()
+		    /* Don't switch if we're currently in the minibuffer.
+		       This tries to work around problems where the
+		       minibuffer gets unselected unexpectedly, and where
+		       you then have to move your mouse all the way down to
+		       the minibuffer to select it.  */
+		    && !MINI_WINDOW_P (XWINDOW (selected_window))
+		    /* With `focus-follows-mouse' non-nil create an event
+		       also when the target window is on another frame.  */
+		    && (f == XFRAME (selected_frame)
+			|| !NILP (focus_follows_mouse)))
+		  {
+		    static Lisp_Object last_mouse_window;
+		    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+		    /* A window will be autoselected only when it is not
+		       selected now and the last mouse movement event was
+		       not in it.  The remainder of the code is a bit vague
+		       wrt what a "window" is.  For immediate autoselection,
+		       the window is usually the entire window but for GTK
+		       where the scroll bars don't count.  For delayed
+		       autoselection the window is usually the window's text
+		       area including the margins.  */
+		    if (WINDOWP (window)
+			&& !EQ (window, last_mouse_window)
+			&& !EQ (window, selected_window))
+		      {
+			inev.ie.kind = SELECT_WINDOW_EVENT;
+			inev.ie.frame_or_window = window;
+		      }
+
+		    /* Remember the last window where we saw the mouse.  */
+		    last_mouse_window = window;
+		  }
+
+		if (!x_note_mouse_movement (f, &ev))
+		  help_echo_string = previous_help_echo_string;
+	      }
+	    else
+	      {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+		struct scroll_bar *bar
+		  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+		if (bar)
+		  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+		/* If we move outside the frame, then we're
+		   certainly no longer on any text in the frame.  */
+		clear_mouse_face (hlinfo);
+	      }
+
+	    /* If the contents of the global variable help_echo_string
+	       has changed, generate a HELP_EVENT.  */
+	    if (!NILP (help_echo_string)
+		|| !NILP (previous_help_echo_string))
+	      do_help = 1;
+	    goto XI_OTHER;
+	  case XI_ButtonRelease:
+	  case XI_ButtonPress:
+	    {
+	      /* If we decide we want to generate an event to be seen
+		 by the rest of Emacs, we put it here.  */
+	      Lisp_Object tab_bar_arg = Qnil;
+	      bool tab_bar_p = false;
+	      bool tool_bar_p = false;
+
+	      bv.button = xev->detail;
+	      bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+	      bv.x = lrint (xev->event_x);
+	      bv.y = lrint (xev->event_y);
+	      bv.window = xev->event;
+	      bv.state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+
+	      memset (&compose_status, 0, sizeof (compose_status));
+	      dpyinfo->last_mouse_glyph_frame = NULL;
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+
+	      f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+	      if (f && xev->evtype == XI_ButtonPress
+		  && !popup_activated ()
+		  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+		  && !FRAME_NO_ACCEPT_FOCUS (f))
+		{
+		  /* When clicking into a child frame or when clicking
+		     into a parent frame with the child frame selected and
+		     `no-accept-focus' is not set, select the clicked
+		     frame.  */
+		  struct frame *hf = dpyinfo->highlight_frame;
+
+		  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+		    {
+		      block_input ();
+		      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+				      RevertToParent, CurrentTime);
+		      if (FRAME_PARENT_FRAME (f))
+			XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+		      unblock_input ();
+		    }
+		}
+
+#ifdef USE_GTK
+	      if (f && xg_event_is_for_scrollbar (f, event))
+		f = 0;
+#endif
+
+	      if (f)
+		{
+		  /* Is this in the tab-bar?  */
+		  if (WINDOWP (f->tab_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tab_bar_p = EQ (window, f->tab_bar_window);
+
+		      if (tab_bar_p)
+			tab_bar_arg = handle_tab_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+
+#if ! defined (USE_GTK)
+		  /* Is this in the tool-bar?  */
+		  if (WINDOWP (f->tool_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tool_bar_p = EQ (window, f->tool_bar_window);
+
+		      if (tool_bar_p && xev->detail < 4)
+			handle_tool_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+#endif /* !USE_GTK */
+
+		  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+		    if (! popup_activated ())
+#endif
+		      {
+			if (ignore_next_mouse_click_timeout)
+			  {
+			    if (xev->evtype == XI_ButtonPress
+				&& xev->time > ignore_next_mouse_click_timeout)
+			      {
+				ignore_next_mouse_click_timeout = 0;
+				x_construct_mouse_click (&inev.ie, &bv, f);
+			      }
+			    if (xev->evtype == XI_ButtonRelease)
+			      ignore_next_mouse_click_timeout = 0;
+			  }
+			else
+			  x_construct_mouse_click (&inev.ie, &bv, f);
+
+			if (!NILP (tab_bar_arg))
+			  inev.ie.arg = tab_bar_arg;
+		      }
+		  if (FRAME_X_EMBEDDED_P (f))
+		    xembed_send_message (f, xev->time,
+					 XEMBED_REQUEST_FOCUS, 0, 0, 0);
+		}
+
+	      if (xev->evtype == XI_ButtonPress)
+		{
+		  dpyinfo->grabbed |= (1 << xev->detail);
+		  dpyinfo->last_mouse_frame = f;
+		  if (f && !tab_bar_p)
+		    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+		  if (f && !tool_bar_p)
+		    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+		}
+	      else
+		dpyinfo->grabbed &= ~(1 << xev->detail);
+
+	      if (f)
+		f->mouse_moved = false;
+
+#if defined (USE_GTK)
+	      /* No Xt toolkit currently available has support for XI2.
+	         So the code here assumes use of GTK. */
+	      f = x_menubar_window_to_frame (dpyinfo, event);
+	      if (! popup_activated ()
+		  /* Gtk+ menus only react to the first three buttons. */
+		  && xev->detail < 3
+		  && f && xev->type == XI_ButtonPress
+		  /* Verify the event is really within the menu bar
+		     and not just sent to it due to grabbing.  */
+		  && xev->event_x >= 0
+		  && xev->event_y < FRAME_PIXEL_WIDTH (f)
+		  && xev->event_x >= 0
+		  && xev->event_y < FRAME_MENUBAR_HEIGHT (f))
+		{
+		  if (!f->output_data.x->saved_menu_event)
+		    f->output_data.x->saved_menu_event = xmalloc (sizeof *event);
+		  *f->output_data.x->saved_menu_event = *event;
+		  /* Must do this here or GTK will do a read-after-free. */
+		  f->output_data.x->saved_menu_event->xcookie.data = NULL;
+		  inev.ie.kind = MENU_BAR_ACTIVATE_EVENT;
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  *finish = X_EVENT_DROP;
+		}
+#endif
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyPress:
+	    {
+	      int state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+	      Lisp_Object c;
+#ifdef HAVE_XKB
+	      unsigned int mods_rtrn;
+#endif
+	      int keycode = xev->detail;
+	      KeySym keysym;
+	      char copy_buffer[81];
+	      char *copy_bufptr = copy_buffer;
+	      unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+	      int copy_bufsiz = sizeof (copy_buffer);
+#endif
+	      ptrdiff_t i;
+	      int nchars, len;
+
+#ifdef HAVE_XKB
+	      if (dpyinfo->xkb_desc)
+		{
+		  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+					    state, &mods_rtrn, &keysym))
+		    goto XI_OTHER;
+		}
+	      else
+		{
+#endif
+		  int keysyms_per_keycode_return;
+		  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+						      &keysyms_per_keycode_return);
+		  if (!(keysym = ksms[0]))
+		    {
+		      XFree (ksms);
+		      goto XI_OTHER;
+		    }
+		  XFree (ksms);
+#ifdef HAVE_XKB
+		}
+#endif
+
+	      if (keysym == NoSymbol)
+		goto XI_OTHER;
+
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+	      ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+	      /* Dispatch XI_KeyPress events when in menu.  */
+	      if (popup_activated ())
+		goto XI_OTHER;
+#endif
+
+	      f = x_any_window_to_frame (dpyinfo, xev->event);
+
+	      /* If mouse-highlight is an integer, input clears out
+		 mouse highlighting.  */
+	      if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+		  && (f == 0
+#if ! defined (USE_GTK)
+		      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+		      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+		  )
+		{
+		  clear_mouse_face (hlinfo);
+		  hlinfo->mouse_face_hidden = true;
+		}
+
+	      if (f != 0)
+		{
+		  /* If not using XIM/XIC, and a compose sequence is in progress,
+		     we break here.  Otherwise, chars_matched is always 0.  */
+		  if (compose_status.chars_matched > 0 && nbytes == 0)
+		    goto XI_OTHER;
+
+		  memset (&compose_status, 0, sizeof (compose_status));
+
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  inev.ie.modifiers
+		    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+		  inev.ie.timestamp = xev->time;
+
+		  /* First deal with keysyms which have defined
+		     translations to characters.  */
+		  if (keysym >= 32 && keysym < 128)
+		    /* Avoid explicitly decoding each ASCII character.  */
+		    {
+		      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+
+		      goto xi_done_keysym;
+		    }
+
+		  /* Keysyms directly mapped to Unicode characters.  */
+		  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+		    {
+		      if (keysym < 0x01000080)
+			inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      else
+			inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym & 0xFFFFFF;
+		      goto xi_done_keysym;
+		    }
+
+		  /* Now non-ASCII.  */
+		  if (HASH_TABLE_P (Vx_keysym_table)
+		      && (c = Fgethash (make_fixnum (keysym),
+					Vx_keysym_table,
+					Qnil),
+			  FIXNATP (c)))
+		    {
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = XFIXNAT (c);
+		      goto xi_done_keysym;
+		    }
+
+		  /* Random non-modifier sorts of keysyms.  */
+		  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+		       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+		       || (keysym >= XK_ISO_Left_Tab
+			   && keysym <= XK_ISO_Enter)
+#endif
+		       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+		       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+		       /* This recognizes the "extended function
+			  keys".  It seems there's no cleaner way.
+			  Test IsModifierKey to avoid handling
+			  mode_switch incorrectly.  */
+		       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+		       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+		       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+		       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+		       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+		       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+		       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+		       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+		       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+		       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+		       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+		       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+		       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+		       || keysym == XK_dead_abovedot
+#endif
+		       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+		       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+		       /* Any "vendor-specific" key is ok.  */
+		       || (keysym & (1 << 28))
+		       || (keysym != NoSymbol && nbytes == 0))
+		      && ! (IsModifierKey (keysym)
+			    /* The symbols from XK_ISO_Lock
+			       to XK_ISO_Last_Group_Lock
+			       don't have real modifiers but
+			       should be treated similarly to
+			       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+			    || (XK_ISO_Lock <= keysym
+				&& keysym <= XK_ISO_Last_Group_Lock)
+#endif
+			    ))
+		    {
+		      STORE_KEYSYM_FOR_DEBUG (keysym);
+		      /* make_lispy_event will convert this to a symbolic
+			 key.  */
+		      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+		      goto xi_done_keysym;
+		    }
+
+#ifdef HAVE_XKB
+		  int overflow = 0;
+		  KeySym sym = keysym;
+
+		  if (dpyinfo->xkb_desc)
+		    {
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz, &overflow)))
+			goto XI_OTHER;
+		    }
+		  else
+#else
+		    {
+		      block_input ();
+		      char *str = XKeysymToString (keysym);
+		      if (!str)
+			{
+			  unblock_input ();
+			  goto XI_OTHER;
+			}
+		      nbytes = strlen (str) + 1;
+		      copy_bufptr = alloca (nbytes);
+		      strcpy (copy_bufptr, str);
+		      unblock_input ();
+		    }
+#endif
+#ifdef HAVE_XKB
+		  if (overflow)
+		    {
+		      overflow = 0;
+		      copy_bufptr = alloca (copy_bufsiz + overflow);
+		      keysym = sym;
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz + overflow, &overflow)))
+			goto XI_OTHER;
+
+		      if (overflow)
+			goto XI_OTHER;
+		    }
+#endif
+
+		  for (i = 0, nchars = 0; i < nbytes; i++)
+		    {
+		      if (ASCII_CHAR_P (copy_bufptr[i]))
+			nchars++;
+		      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+		    }
+
+		  if (nchars < nbytes)
+		    {
+		      /* Decode the input data.  */
+
+		      setup_coding_system (Vlocale_coding_system, &coding);
+		      coding.src_multibyte = false;
+		      coding.dst_multibyte = true;
+		      /* The input is converted to events, thus we can't
+			 handle composition.  Anyway, there's no XIM that
+			 gives us composition information.  */
+		      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+		      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+				    nbytes);
+		      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+		      coding.mode |= CODING_MODE_LAST_BLOCK;
+		      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr, nbytes, Qnil);
+		      nbytes = coding.produced;
+		      nchars = coding.produced_char;
+		      copy_bufptr = (char *) coding.destination;
+		    }
+
+		  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+		  /* Convert the input data to a sequence of
+		     character events.  */
+		  for (i = 0; i < nbytes; i += len)
+		    {
+		      int ch;
+		      if (nchars == nbytes)
+			ch = copy_ubufptr[i], len = 1;
+		      else
+			ch = string_char_and_length (copy_ubufptr + i, &len);
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = ch;
+		      kbd_buffer_store_buffered_event (&inev, hold_quit);
+		    }
+
+		  inev.ie.kind = NO_EVENT;
+		  goto xi_done_keysym;
+		}
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyRelease:
+	    x_display_set_last_user_time (dpyinfo, xev->time);
+	    goto XI_OTHER;
+	  case XI_PropertyEvent:
+
+	  default:
+	    goto XI_OTHER;
+	  }
+      xi_done_keysym:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto done_keysym;
+      XI_OTHER:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13013,6 +13742,35 @@ #define NUM_ARGV 10
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+		       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+	dpyinfo->supports_xi2 = true;
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+				 XkbAllComponentsMask,
+				 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13445,6 +14203,10 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+	XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13604,9 +14366,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index de6ea50385..6d5f28c76e 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ #define XSync(d, b) do { gdk_window_process_all_updates (); \
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -474,6 +478,16 @@ #define MAX_CLIP_RECTS 2
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
-- 
2.31.1

Re: XInput 2 support

[Po Lu]

[-- Attachment #1: Type: text/plain, Size: 191 bytes --]

Po Lu <luangruo@yahoo.com> writes:

> Okay, I asked someone to test and he reported a problem with the menu
> bar.  This updated patch should fix it.

That didn't work either.  This should.


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-Add-support-for-event-processing-via-XInput-2.patch --]
[-- Type: text/x-patch, Size: 35061 bytes --]

From 7aa00bdcd92af89e5ff9f3c562e06e0ab40dc58a Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 16 Oct 2021 13:15:36 +0800
Subject: [PATCH] Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables
(EMACS_CFLAGS): Add Xinput CFLAGS
(LIBES): Add XInput libs
* src/xfns.c (x_window): Set XInput 2 event mask
* src/xterm.c (x_detect_focus_change): Handle XInput 2 GenericEvents
(handle_one_xevent): Handle XInput 2 events
(x_term_init): Ask the server for XInput 2 support and set xkb_desc if
available
(x_delete_terminal): Free XKB kb desc if it exists
(init_xterm): Don't tell GTK to only use Core Input when built with
XInput 2 support
* src/xterm.h (struct x_display_info): Add fields for XKB and XI2
support
* src/gtkutil.c (xg_event_is_for_menubar): Handle XIDeviceEvents
---
 configure.ac    |  22 ++
 src/Makefile.in |   7 +-
 src/gtkutil.c   |  23 +-
 src/xfns.c      |  56 ++++
 src/xterm.c     | 776 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h     |  14 +
 6 files changed, 891 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9ab0314428..0af8b65dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -485,6 +485,7 @@ AC_DEFUN
 OPTION_DEFAULT_ON([modules],[don't compile with dynamic modules support])
 OPTION_DEFAULT_ON([threads],[don't compile with elisp threading support])
 OPTION_DEFAULT_OFF([native-compilation],[compile with Emacs Lisp native compiler support])
+OPTION_DEFAULT_OFF([xinput2],[use version 2.0 the X Input Extension for input])
 
 AC_ARG_WITH([file-notification],[AS_HELP_STRING([--with-file-notification=LIB],
  [use a file notification library (LIB one of: yes, inotify, kqueue, gfile, w32, no)])],
@@ -4203,6 +4204,26 @@ AC_DEFUN
 AC_SUBST(XFIXES_CFLAGS)
 AC_SUBST(XFIXES_LIBS)
 
+## Use XInput 2.0 if available
+HAVE_XINPUT2=no
+if test "${HAVE_X11}" = "yes" && test "${with_xinput2}" != "no"; then
+   EMACS_CHECK_MODULES([XINPUT], [xi])
+   if test $HAVE_XINPUT = yes; then
+     # Now check for XInput2.h
+     AC_CHECK_HEADER(X11/extensions/XInput2.h,
+       [AC_CHECK_LIB(Xi, XIGrabButton, HAVE_XINPUT2=yes)])
+   fi
+   if test $HAVE_XINPUT2 = yes; then
+     AC_DEFINE(HAVE_XINPUT2, 1, [Define to 1 if the X Input Extension version 2.0 is present.])
+     if test "$USE_GTK_TOOLKIT" = "GTK2"; then
+       AC_MSG_WARN([You are building Emacs with GTK+ 2 and the X Input Extension version 2.
+This might lead to problems if your version of GTK+ is not built with support for XInput 2.])
+     fi
+   fi
+fi
+AC_SUBST(XINPUT_CFLAGS)
+AC_SUBST(XINPUT_LIBS)
+
 ### Use Xdbe (-lXdbe) if available
 HAVE_XDBE=no
 if test "${HAVE_X11}" = "yes"; then
@@ -5959,6 +5980,7 @@ AC_DEFUN
   Does Emacs support legacy unexec dumping?               ${with_unexec}
   Which dumping strategy does Emacs use?                  ${with_dumping}
   Does Emacs have native lisp compiler?                   ${HAVE_NATIVE_COMP}
+  Does Emacs use version 2 of the the X Input Extension?  ${HAVE_XINPUT2}
 "])
 
 if test -n "${EMACSDATA}"; then
diff --git a/src/Makefile.in b/src/Makefile.in
index 6d75e3537a..2b3e1f37e0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -256,6 +256,9 @@ XINERAMA_CFLAGS =
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -372,7 +375,7 @@ EMACS_CFLAGS=
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -522,7 +525,7 @@ LIBES =
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/gtkutil.c b/src/gtkutil.c
index e87845caf7..0304f02434 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -47,6 +47,10 @@ Copyright (C) 2003-2021 Free Software Foundation, Inc.
 
 #include <gdk/gdkkeysyms.h>
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef HAVE_XFT
 #include <X11/Xft/Xft.h>
 #endif
@@ -3575,6 +3579,18 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
 
   if (! x->menubar_widget) return 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (event->type == GenericEvent) /* XI_ButtonPress or XI_ButtonRelease */
+    {
+      if (! (xev->event_x >= 0
+	     && xev->event_x < FRAME_PIXEL_WIDTH (f)
+	     && xev->event_y >= 0
+	     && xev->event_y < FRAME_MENUBAR_HEIGHT (f)))
+	return 0;
+    }
+  else
+#endif
   if (! (event->xbutton.x >= 0
          && event->xbutton.x < FRAME_PIXEL_WIDTH (f)
          && event->xbutton.y >= 0
@@ -3583,7 +3599,12 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
     return 0;
 
   gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
-  gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent)
+    gw = gdk_x11_window_lookup_for_display (gdpy, xev->event);
+  else
+#endif
+    gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
   if (! gw) return 0;
   gevent.any.window = gw;
   gevent.any.type = GDK_NOTHING;
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca..4fef8005a0 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ Copyright (C) 1989, 1992-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -3074,6 +3078,32 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3284,32 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
diff --git a/src/xterm.c b/src/xterm.c
index 961c61c245..0435ad341c 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ Copyright (C) 1989, 1993-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ #define XtNinitialState "initialState"
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
 			      const XEvent *, int *,
 			      struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+			      XEvent *, int *,
+			      struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -4665,7 +4675,16 @@ x_any_window_to_frame (struct x_display_info *dpyinfo, int wdesc)
 x_menubar_window_to_frame (struct x_display_info *dpyinfo,
 			   const XEvent *event)
 {
-  Window wdesc = event->xany.window;
+  Window wdesc;
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent
+      && dpyinfo->supports_xi2
+      && (event->xcookie.evtype == XI_ButtonPress
+	  || event->xcookie.evtype == XI_ButtonRelease))
+    wdesc = ((XIDeviceEvent *) event->xcookie.data)->event;
+#endif
+  else
+    wdesc = event->xany.window;
   Lisp_Object tail, frame;
   struct frame *f;
   struct x_output *x;
@@ -4768,6 +4787,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+	if (!((xi_event->evtype == XI_Enter
+	       || xi_event->evtype == XI_Leave)
+	      && (focus_state & FOCUS_EXPLICIT)))
+	  x_focus_changed ((xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_FocusIn
+			    ? FocusIn : FocusOut),
+			   (xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_Leave
+			    ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+			   dpyinfo, frame, bufp);
+	break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7872,7 +7914,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
 		   const XEvent *event,
+#else
+		   XEvent *event,
+#endif
 		   int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -7898,7 +7944,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -9343,6 +9396,685 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	if (!dpyinfo->supports_xi2)
+	  goto OTHER;
+	if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+	  /* Not an XI2 event. */
+	  goto OTHER;
+	bool must_free_data = false;
+	XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+	/* Sometimes the event is already claimed by GTK, which
+	   will free its data in due course. */
+	if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+	  {
+	    must_free_data = true;
+	    xi_event = (XIEvent *) event->xcookie.data;
+	  }
+
+	XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+	XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+	XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+	XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+	XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+
+	/* A fake XMotionEvent for x_note_mouse_movement. */
+	XMotionEvent ev;
+	/* A fake XButtonEvent for x_construct_mouse_click. */
+	XButtonEvent bv;
+
+	if (!xi_event)
+	  {
+	    eassert (!must_free_data);
+	    goto OTHER;
+	  }
+
+	switch (event->xcookie.evtype)
+	  {
+	  case XI_FocusIn:
+	    any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+	    /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+	       minimized/iconified windows; thus, for those WMs we won't get
+	       a MapNotify when unminimizing/deconifying.  Check here if we
+	       are deiconizing a window (Bug42655).
+
+	       But don't do that on GTK since it may cause a plain invisible
+	       frame get reported as iconified, compare
+	       https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+	       That is fixed above but bites us here again.  */
+	    f = any;
+	    if (f && FRAME_ICONIFIED_P (f))
+	      {
+		SET_FRAME_VISIBLE (f, 1);
+		SET_FRAME_ICONIFIED (f, false);
+		f->output_data.x->has_been_visible = true;
+		inev.ie.kind = DEICONIFY_EVENT;
+		XSETFRAME (inev.ie.frame_or_window, f);
+	      }
+#endif /* USE_GTK */
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_FocusOut:
+	    any = x_any_window_to_frame (dpyinfo, focusout->event);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_Enter:
+	    any = x_any_window_to_frame (dpyinfo, enter->event);
+	    ev.x = lrint (enter->event_x);
+	    ev.y = lrint (enter->event_y);
+	    ev.window = leave->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    f = any;
+
+	    if (f && x_mouse_click_focus_ignore_position)
+	      ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+	    /* EnterNotify counts as mouse movement,
+	       so update things that depend on mouse position.  */
+	    if (f && !f->output_data.x->hourglass_p)
+	      x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+	    /* We may get an EnterNotify on the buttons in the toolbar.  In that
+	       case we moved out of any highlighted area and need to note this.  */
+	    if (!f && dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Leave:
+	    ev.x = lrint (leave->event_x);
+	    ev.y = lrint (leave->event_y);
+	    ev.window = leave->event;
+	    any = x_any_window_to_frame (dpyinfo, leave->event);
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+
+	    f = x_top_window_to_frame (dpyinfo, leave->event);
+	    if (f)
+	      {
+		if (f == hlinfo->mouse_face_mouse_frame)
+		  {
+		    /* If we move outside the frame, then we're
+		       certainly no longer on any text in the frame.  */
+		    clear_mouse_face (hlinfo);
+		    hlinfo->mouse_face_mouse_frame = 0;
+		  }
+
+		/* Generate a nil HELP_EVENT to cancel a help-echo.
+		   Do it only if there's something to cancel.
+		   Otherwise, the startup message is cleared when
+		   the mouse leaves the frame.  */
+		if (any_help_event_p)
+		  do_help = -1;
+	      }
+#ifdef USE_GTK
+	    /* See comment in EnterNotify above */
+	    else if (dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Motion:
+	    ev.x = lrint (xev->event_x);
+	    ev.y = lrint (xev->event_y);
+	    ev.window = xev->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    previous_help_echo_string = help_echo_string;
+	    help_echo_string = Qnil;
+
+	    if (hlinfo->mouse_face_hidden)
+	      {
+		hlinfo->mouse_face_hidden = false;
+		clear_mouse_face (hlinfo);
+	      }
+
+	    f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+	    if (f && xg_event_is_for_scrollbar (f, event))
+	      f = 0;
+#endif
+	    if (f)
+	      {
+		/* Maybe generate a SELECT_WINDOW_EVENT for
+		   `mouse-autoselect-window' but don't let popup menus
+		   interfere with this (Bug#1261).  */
+		if (!NILP (Vmouse_autoselect_window)
+		    && !popup_activated ()
+		    /* Don't switch if we're currently in the minibuffer.
+		       This tries to work around problems where the
+		       minibuffer gets unselected unexpectedly, and where
+		       you then have to move your mouse all the way down to
+		       the minibuffer to select it.  */
+		    && !MINI_WINDOW_P (XWINDOW (selected_window))
+		    /* With `focus-follows-mouse' non-nil create an event
+		       also when the target window is on another frame.  */
+		    && (f == XFRAME (selected_frame)
+			|| !NILP (focus_follows_mouse)))
+		  {
+		    static Lisp_Object last_mouse_window;
+		    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+		    /* A window will be autoselected only when it is not
+		       selected now and the last mouse movement event was
+		       not in it.  The remainder of the code is a bit vague
+		       wrt what a "window" is.  For immediate autoselection,
+		       the window is usually the entire window but for GTK
+		       where the scroll bars don't count.  For delayed
+		       autoselection the window is usually the window's text
+		       area including the margins.  */
+		    if (WINDOWP (window)
+			&& !EQ (window, last_mouse_window)
+			&& !EQ (window, selected_window))
+		      {
+			inev.ie.kind = SELECT_WINDOW_EVENT;
+			inev.ie.frame_or_window = window;
+		      }
+
+		    /* Remember the last window where we saw the mouse.  */
+		    last_mouse_window = window;
+		  }
+
+		if (!x_note_mouse_movement (f, &ev))
+		  help_echo_string = previous_help_echo_string;
+	      }
+	    else
+	      {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+		struct scroll_bar *bar
+		  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+		if (bar)
+		  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+		/* If we move outside the frame, then we're
+		   certainly no longer on any text in the frame.  */
+		clear_mouse_face (hlinfo);
+	      }
+
+	    /* If the contents of the global variable help_echo_string
+	       has changed, generate a HELP_EVENT.  */
+	    if (!NILP (help_echo_string)
+		|| !NILP (previous_help_echo_string))
+	      do_help = 1;
+	    goto XI_OTHER;
+	  case XI_ButtonRelease:
+	  case XI_ButtonPress:
+	    {
+	      /* If we decide we want to generate an event to be seen
+		 by the rest of Emacs, we put it here.  */
+	      Lisp_Object tab_bar_arg = Qnil;
+	      bool tab_bar_p = false;
+	      bool tool_bar_p = false;
+
+	      bv.button = xev->detail;
+	      bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+	      bv.x = lrint (xev->event_x);
+	      bv.y = lrint (xev->event_y);
+	      bv.window = xev->event;
+	      bv.state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+
+	      memset (&compose_status, 0, sizeof (compose_status));
+	      dpyinfo->last_mouse_glyph_frame = NULL;
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+
+	      f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+	      if (f && xev->evtype == XI_ButtonPress
+		  && !popup_activated ()
+		  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+		  && !FRAME_NO_ACCEPT_FOCUS (f))
+		{
+		  /* When clicking into a child frame or when clicking
+		     into a parent frame with the child frame selected and
+		     `no-accept-focus' is not set, select the clicked
+		     frame.  */
+		  struct frame *hf = dpyinfo->highlight_frame;
+
+		  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+		    {
+		      block_input ();
+		      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+				      RevertToParent, CurrentTime);
+		      if (FRAME_PARENT_FRAME (f))
+			XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+		      unblock_input ();
+		    }
+		}
+
+#ifdef USE_GTK
+	      if (f && xg_event_is_for_scrollbar (f, event))
+		f = 0;
+#endif
+
+	      if (f)
+		{
+		  /* Is this in the tab-bar?  */
+		  if (WINDOWP (f->tab_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tab_bar_p = EQ (window, f->tab_bar_window);
+
+		      if (tab_bar_p)
+			tab_bar_arg = handle_tab_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+
+#if ! defined (USE_GTK)
+		  /* Is this in the tool-bar?  */
+		  if (WINDOWP (f->tool_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tool_bar_p = EQ (window, f->tool_bar_window);
+
+		      if (tool_bar_p && xev->detail < 4)
+			handle_tool_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+#endif /* !USE_GTK */
+
+		  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+		    if (! popup_activated ())
+#endif
+		      {
+			if (ignore_next_mouse_click_timeout)
+			  {
+			    if (xev->evtype == XI_ButtonPress
+				&& xev->time > ignore_next_mouse_click_timeout)
+			      {
+				ignore_next_mouse_click_timeout = 0;
+				x_construct_mouse_click (&inev.ie, &bv, f);
+			      }
+			    if (xev->evtype == XI_ButtonRelease)
+			      ignore_next_mouse_click_timeout = 0;
+			  }
+			else
+			  x_construct_mouse_click (&inev.ie, &bv, f);
+
+			if (!NILP (tab_bar_arg))
+			  inev.ie.arg = tab_bar_arg;
+		      }
+		  if (FRAME_X_EMBEDDED_P (f))
+		    xembed_send_message (f, xev->time,
+					 XEMBED_REQUEST_FOCUS, 0, 0, 0);
+		}
+
+	      if (xev->evtype == XI_ButtonPress)
+		{
+		  dpyinfo->grabbed |= (1 << xev->detail);
+		  dpyinfo->last_mouse_frame = f;
+		  if (f && !tab_bar_p)
+		    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+		  if (f && !tool_bar_p)
+		    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+		}
+	      else
+		dpyinfo->grabbed &= ~(1 << xev->detail);
+
+	      if (f)
+		f->mouse_moved = false;
+
+#if defined (USE_GTK)
+	      /* No Xt toolkit currently available has support for XI2.
+	         So the code here assumes use of GTK.  */
+	      f = x_menubar_window_to_frame (dpyinfo, event);
+	      if (f /* Gtk+ menus only react to the first three buttons. */
+		  && xev->detail < 3)
+		{
+		  /* What is done with Core Input ButtonPressed is not
+		     possible here, because GenericEvents cannot be saved.  */
+		  bool was_waiting_for_input = waiting_for_input;
+		  /* This hack was adopted from the NS port.  Whether
+		     or not it is actually safe is a different story
+		     altogether.  */
+		  if (waiting_for_input)
+		    waiting_for_input = 0;
+		  set_frame_menubar (f, true);
+		  waiting_for_input = was_waiting_for_input;
+		}
+#endif
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyPress:
+	    {
+	      int state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+	      Lisp_Object c;
+#ifdef HAVE_XKB
+	      unsigned int mods_rtrn;
+#endif
+	      int keycode = xev->detail;
+	      KeySym keysym;
+	      char copy_buffer[81];
+	      char *copy_bufptr = copy_buffer;
+	      unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+	      int copy_bufsiz = sizeof (copy_buffer);
+#endif
+	      ptrdiff_t i;
+	      int nchars, len;
+
+#ifdef HAVE_XKB
+	      if (dpyinfo->xkb_desc)
+		{
+		  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+					    state, &mods_rtrn, &keysym))
+		    goto XI_OTHER;
+		}
+	      else
+		{
+#endif
+		  int keysyms_per_keycode_return;
+		  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+						      &keysyms_per_keycode_return);
+		  if (!(keysym = ksms[0]))
+		    {
+		      XFree (ksms);
+		      goto XI_OTHER;
+		    }
+		  XFree (ksms);
+#ifdef HAVE_XKB
+		}
+#endif
+
+	      if (keysym == NoSymbol)
+		goto XI_OTHER;
+
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+	      ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+	      /* Dispatch XI_KeyPress events when in menu.  */
+	      if (popup_activated ())
+		goto XI_OTHER;
+#endif
+
+	      f = x_any_window_to_frame (dpyinfo, xev->event);
+
+	      /* If mouse-highlight is an integer, input clears out
+		 mouse highlighting.  */
+	      if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+		  && (f == 0
+#if ! defined (USE_GTK)
+		      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+		      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+		  )
+		{
+		  clear_mouse_face (hlinfo);
+		  hlinfo->mouse_face_hidden = true;
+		}
+
+	      if (f != 0)
+		{
+		  /* If not using XIM/XIC, and a compose sequence is in progress,
+		     we break here.  Otherwise, chars_matched is always 0.  */
+		  if (compose_status.chars_matched > 0 && nbytes == 0)
+		    goto XI_OTHER;
+
+		  memset (&compose_status, 0, sizeof (compose_status));
+
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  inev.ie.modifiers
+		    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+		  inev.ie.timestamp = xev->time;
+
+		  /* First deal with keysyms which have defined
+		     translations to characters.  */
+		  if (keysym >= 32 && keysym < 128)
+		    /* Avoid explicitly decoding each ASCII character.  */
+		    {
+		      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+
+		      goto xi_done_keysym;
+		    }
+
+		  /* Keysyms directly mapped to Unicode characters.  */
+		  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+		    {
+		      if (keysym < 0x01000080)
+			inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      else
+			inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym & 0xFFFFFF;
+		      goto xi_done_keysym;
+		    }
+
+		  /* Now non-ASCII.  */
+		  if (HASH_TABLE_P (Vx_keysym_table)
+		      && (c = Fgethash (make_fixnum (keysym),
+					Vx_keysym_table,
+					Qnil),
+			  FIXNATP (c)))
+		    {
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = XFIXNAT (c);
+		      goto xi_done_keysym;
+		    }
+
+		  /* Random non-modifier sorts of keysyms.  */
+		  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+		       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+		       || (keysym >= XK_ISO_Left_Tab
+			   && keysym <= XK_ISO_Enter)
+#endif
+		       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+		       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+		       /* This recognizes the "extended function
+			  keys".  It seems there's no cleaner way.
+			  Test IsModifierKey to avoid handling
+			  mode_switch incorrectly.  */
+		       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+		       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+		       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+		       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+		       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+		       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+		       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+		       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+		       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+		       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+		       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+		       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+		       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+		       || keysym == XK_dead_abovedot
+#endif
+		       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+		       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+		       /* Any "vendor-specific" key is ok.  */
+		       || (keysym & (1 << 28))
+		       || (keysym != NoSymbol && nbytes == 0))
+		      && ! (IsModifierKey (keysym)
+			    /* The symbols from XK_ISO_Lock
+			       to XK_ISO_Last_Group_Lock
+			       don't have real modifiers but
+			       should be treated similarly to
+			       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+			    || (XK_ISO_Lock <= keysym
+				&& keysym <= XK_ISO_Last_Group_Lock)
+#endif
+			    ))
+		    {
+		      STORE_KEYSYM_FOR_DEBUG (keysym);
+		      /* make_lispy_event will convert this to a symbolic
+			 key.  */
+		      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+		      goto xi_done_keysym;
+		    }
+
+#ifdef HAVE_XKB
+		  int overflow = 0;
+		  KeySym sym = keysym;
+
+		  if (dpyinfo->xkb_desc)
+		    {
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz, &overflow)))
+			goto XI_OTHER;
+		    }
+		  else
+#else
+		    {
+		      block_input ();
+		      char *str = XKeysymToString (keysym);
+		      if (!str)
+			{
+			  unblock_input ();
+			  goto XI_OTHER;
+			}
+		      nbytes = strlen (str) + 1;
+		      copy_bufptr = alloca (nbytes);
+		      strcpy (copy_bufptr, str);
+		      unblock_input ();
+		    }
+#endif
+#ifdef HAVE_XKB
+		  if (overflow)
+		    {
+		      overflow = 0;
+		      copy_bufptr = alloca (copy_bufsiz + overflow);
+		      keysym = sym;
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz + overflow, &overflow)))
+			goto XI_OTHER;
+
+		      if (overflow)
+			goto XI_OTHER;
+		    }
+#endif
+
+		  for (i = 0, nchars = 0; i < nbytes; i++)
+		    {
+		      if (ASCII_CHAR_P (copy_bufptr[i]))
+			nchars++;
+		      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+		    }
+
+		  if (nchars < nbytes)
+		    {
+		      /* Decode the input data.  */
+
+		      setup_coding_system (Vlocale_coding_system, &coding);
+		      coding.src_multibyte = false;
+		      coding.dst_multibyte = true;
+		      /* The input is converted to events, thus we can't
+			 handle composition.  Anyway, there's no XIM that
+			 gives us composition information.  */
+		      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+		      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+				    nbytes);
+		      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+		      coding.mode |= CODING_MODE_LAST_BLOCK;
+		      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr, nbytes, Qnil);
+		      nbytes = coding.produced;
+		      nchars = coding.produced_char;
+		      copy_bufptr = (char *) coding.destination;
+		    }
+
+		  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+		  /* Convert the input data to a sequence of
+		     character events.  */
+		  for (i = 0; i < nbytes; i += len)
+		    {
+		      int ch;
+		      if (nchars == nbytes)
+			ch = copy_ubufptr[i], len = 1;
+		      else
+			ch = string_char_and_length (copy_ubufptr + i, &len);
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = ch;
+		      kbd_buffer_store_buffered_event (&inev, hold_quit);
+		    }
+
+		  inev.ie.kind = NO_EVENT;
+		  goto xi_done_keysym;
+		}
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyRelease:
+	    x_display_set_last_user_time (dpyinfo, xev->time);
+	    goto XI_OTHER;
+	  case XI_PropertyEvent:
+
+	  default:
+	    goto XI_OTHER;
+	  }
+      xi_done_keysym:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto done_keysym;
+      XI_OTHER:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13013,6 +13745,35 @@ #define NUM_ARGV 10
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+		       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+	dpyinfo->supports_xi2 = true;
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+				 XkbAllComponentsMask,
+				 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13445,6 +14206,10 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+	XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13604,9 +14369,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index de6ea50385..6d5f28c76e 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ #define XSync(d, b) do { gdk_window_process_all_updates (); \
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -474,6 +478,16 @@ #define MAX_CLIP_RECTS 2
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
-- 
2.31.1

Re: XInput 2 support

[Alan Third]

On Sat, Oct 16, 2021 at 01:37:13PM +0800, Po Lu wrote:
> I hacked up support for handling XInput 2 events, though it hasn't
> undergone any serious testing yet.
> 
> So the only advantage of this code over the existing Core Input code as
> of present would be not relying on a fragile environment variable
> (GDK_CORE_DEVICE_EVENTS) to work properly in GTK 3 builds.  Call me
> paranoid, but this variable reeks of something that the GTK developers
> will remove at some point in the future.  (AFAIK, it's already been
> removed in GTK 4).
> 
> However, it paves the way for future support of high-resolution
> scrollwheels, multi-touch trackpad support, and much more.
> 
> Would this support be worth installing?  Thanks.

I think it's definitely worth it. I can't speak much about your code,
though: I only delved into the X input code enough to understand that
it could never directly support multitouch and pixel-scrolling without
adding XInput2 support and that I wasn't confident enough to do that
myself.
-- 
Alan Third

Re: XInput 2 support

[Po Lu via Emacs development discussions.]

[-- Attachment #1: Type: text/plain, Size: 557 bytes --]

Alan Third <alan@idiocy.org> writes:

> I think it's definitely worth it.

Thanks!

> it could never directly support multitouch and pixel-scrolling without
> adding XInput2 support and that I wasn't confident enough to do that
> myself.

BTW, the attached version of the change should make it easier for
someone to add pixelwise scrolling support in the future.

Basically, the pixel-wise delta you want is the `delta' in the following
code snippet:

    double delta =
      x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
				   i, *values, &val);


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-Add-support-for-event-processing-via-XInput-2.patch --]
[-- Type: text/x-patch, Size: 48601 bytes --]

From 955b6d59a62def8937c0ac9c1bd83ab7e0e11517 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 16 Oct 2021 13:15:36 +0800
Subject: [PATCH] Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables
(EMACS_CFLAGS): Add Xinput CFLAGS
(LIBES): Add XInput libs
* src/xmenu.c (popup_activated_flag): Expose flag if XInput 2 is
available
* src/xfns.c (x_window): Set XInput 2 event mask
* src/xterm.c (x_detect_focus_change): Handle XInput 2 GenericEvents
(handle_one_xevent): Handle XInput 2 events
(x_term_init): Ask the server for XInput 2 support and set xkb_desc if
available
(x_delete_terminal): Free XKB kb desc if it exists, and free XI2
devices if they exist
(x_free_xi_devices, x_init_master_valuators): New functions
(x_get_scroll_valuator_delta): New function
(init_xterm): Don't tell GTK to only use Core Input when built with
XInput 2 support
* src/xterm.h (struct x_display_info): Add fields for XKB and XI2
support
* src/gtkutil.c (xg_event_is_for_menubar): Handle XIDeviceEvents
(xg_is_menu_window): New function
(xg_event_is_for_scrollbar): Handle XIDeviceEvents
---
 configure.ac    |   22 +
 src/Makefile.in |    7 +-
 src/gtkutil.c   |   72 +++-
 src/gtkutil.h   |    4 +
 src/xfns.c      |   62 +++
 src/xmenu.c     |    4 +
 src/xterm.c     | 1086 ++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h     |   42 ++
 8 files changed, 1292 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9ab0314428..0af8b65dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -485,6 +485,7 @@ AC_DEFUN
 OPTION_DEFAULT_ON([modules],[don't compile with dynamic modules support])
 OPTION_DEFAULT_ON([threads],[don't compile with elisp threading support])
 OPTION_DEFAULT_OFF([native-compilation],[compile with Emacs Lisp native compiler support])
+OPTION_DEFAULT_OFF([xinput2],[use version 2.0 the X Input Extension for input])
 
 AC_ARG_WITH([file-notification],[AS_HELP_STRING([--with-file-notification=LIB],
  [use a file notification library (LIB one of: yes, inotify, kqueue, gfile, w32, no)])],
@@ -4203,6 +4204,26 @@ AC_DEFUN
 AC_SUBST(XFIXES_CFLAGS)
 AC_SUBST(XFIXES_LIBS)
 
+## Use XInput 2.0 if available
+HAVE_XINPUT2=no
+if test "${HAVE_X11}" = "yes" && test "${with_xinput2}" != "no"; then
+   EMACS_CHECK_MODULES([XINPUT], [xi])
+   if test $HAVE_XINPUT = yes; then
+     # Now check for XInput2.h
+     AC_CHECK_HEADER(X11/extensions/XInput2.h,
+       [AC_CHECK_LIB(Xi, XIGrabButton, HAVE_XINPUT2=yes)])
+   fi
+   if test $HAVE_XINPUT2 = yes; then
+     AC_DEFINE(HAVE_XINPUT2, 1, [Define to 1 if the X Input Extension version 2.0 is present.])
+     if test "$USE_GTK_TOOLKIT" = "GTK2"; then
+       AC_MSG_WARN([You are building Emacs with GTK+ 2 and the X Input Extension version 2.
+This might lead to problems if your version of GTK+ is not built with support for XInput 2.])
+     fi
+   fi
+fi
+AC_SUBST(XINPUT_CFLAGS)
+AC_SUBST(XINPUT_LIBS)
+
 ### Use Xdbe (-lXdbe) if available
 HAVE_XDBE=no
 if test "${HAVE_X11}" = "yes"; then
@@ -5959,6 +5980,7 @@ AC_DEFUN
   Does Emacs support legacy unexec dumping?               ${with_unexec}
   Which dumping strategy does Emacs use?                  ${with_dumping}
   Does Emacs have native lisp compiler?                   ${HAVE_NATIVE_COMP}
+  Does Emacs use version 2 of the the X Input Extension?  ${HAVE_XINPUT2}
 "])
 
 if test -n "${EMACSDATA}"; then
diff --git a/src/Makefile.in b/src/Makefile.in
index 6d75e3537a..2b3e1f37e0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -256,6 +256,9 @@ XINERAMA_CFLAGS =
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -372,7 +375,7 @@ EMACS_CFLAGS=
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -522,7 +525,7 @@ LIBES =
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/gtkutil.c b/src/gtkutil.c
index e87845caf7..fc4afef510 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -47,6 +47,10 @@ Copyright (C) 2003-2021 Free Software Foundation, Inc.
 
 #include <gdk/gdkkeysyms.h>
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef HAVE_XFT
 #include <X11/Xft/Xft.h>
 #endif
@@ -839,6 +843,23 @@ my_log_handler (const gchar *log_domain, GLogLevelFlags log_level,
 }
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+bool
+xg_is_menu_window (Display *dpy, Window wdesc)
+{
+  GtkWidget *gwdesc = xg_win_to_widget (dpy, wdesc);
+
+  if (GTK_IS_WINDOW (gwdesc))
+    {
+      GtkWidget *fw = gtk_bin_get_child (GTK_BIN (gwdesc));
+      if (GTK_IS_MENU (fw))
+	return true;
+    }
+
+  return false;
+}
+#endif
+
 /* Make a geometry string and pass that to GTK.  It seems this is the
    only way to get geometry position right if the user explicitly
    asked for a position when starting Emacs.
@@ -3575,6 +3596,18 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
 
   if (! x->menubar_widget) return 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (event->type == GenericEvent) /* XI_ButtonPress or XI_ButtonRelease */
+    {
+      if (! (xev->event_x >= 0
+	     && xev->event_x < FRAME_PIXEL_WIDTH (f)
+	     && xev->event_y >= 0
+	     && xev->event_y < FRAME_MENUBAR_HEIGHT (f)))
+	return 0;
+    }
+  else
+#endif
   if (! (event->xbutton.x >= 0
          && event->xbutton.x < FRAME_PIXEL_WIDTH (f)
          && event->xbutton.y >= 0
@@ -3583,7 +3616,12 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
     return 0;
 
   gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
-  gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent)
+    gw = gdk_x11_window_lookup_for_display (gdpy, xev->event);
+  else
+#endif
+    gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
   if (! gw) return 0;
   gevent.any.window = gw;
   gevent.any.type = GDK_NOTHING;
@@ -4230,7 +4268,20 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
 {
   bool retval = 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+	     && event->type == GenericEvent
+	     && (event->xgeneric.extension
+		 == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+	     && ((event->xgeneric.evtype == XI_ButtonPress
+		  && xev->detail < 4)
+		 || (event->xgeneric.evtype == XI_Motion)))
+	    || (event->type == ButtonPress
+		&& event->xbutton.button < 4)))
+#else
   if (f && event->type == ButtonPress && event->xbutton.button < 4)
+#endif /* HAVE_XINPUT2 */
     {
       /* Check if press occurred outside the edit widget.  */
       GdkDisplay *gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
@@ -4248,10 +4299,29 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
       gwin = gdk_display_get_window_at_pointer (gdpy, NULL, NULL);
 #endif
       retval = gwin != gtk_widget_get_window (f->output_data.x->edit_widget);
+#ifdef HAVE_XINPUT2
+      GtkWidget *grab = gtk_grab_get_current ();
+      if (event->type == GenericEvent
+	  && event->xgeneric.evtype == XI_Motion)
+	retval = retval || (grab && GTK_IS_SCROLLBAR (grab));
+#endif
     }
+#ifdef HAVE_XINPUT2
+  else if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+		  && event->type == GenericEvent
+		  && (event->xgeneric.extension
+		      == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+		  && ((event->xgeneric.evtype == XI_ButtonRelease
+		       && xev->detail < 4)
+		      || (event->xgeneric.evtype == XI_Motion)))
+		 || ((event->type == ButtonRelease
+		      && event->xbutton.button < 4)
+		     || event->type == MotionNotify)))
+#else
   else if (f
            && ((event->type == ButtonRelease && event->xbutton.button < 4)
                || event->type == MotionNotify))
+#endif /* HAVE_XINPUT2 */
     {
       /* If we are releasing or moving the scroll bar, it has the grab.  */
       GtkWidget *w = gtk_grab_get_current ();
diff --git a/src/gtkutil.h b/src/gtkutil.h
index 31a12cd5d3..95dd75b7fa 100644
--- a/src/gtkutil.h
+++ b/src/gtkutil.h
@@ -192,6 +192,10 @@ #define XG_ITEM_DATA "emacs_menuitem"
 extern void xg_print_frames_dialog (Lisp_Object);
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+extern bool xg_is_menu_window (Display *dpy, Window);
+#endif
+
 /* Mark all callback data that are Lisp_object:s during GC.  */
 extern void xg_mark_data (void);
 
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca..561ee5988f 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ Copyright (C) 1989, 1992-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -3074,6 +3078,35 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISetMask (m, XI_PropertyEvent);
+      XISetMask (m, XI_HierarchyChanged);
+      XISetMask (m, XI_DeviceChanged);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3287,35 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISetMask (m, XI_PropertyEvent);
+      XISetMask (m, XI_HierarchyChanged);
+      XISetMask (m, XI_DeviceChanged);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
diff --git a/src/xmenu.c b/src/xmenu.c
index ea2cbab203..07255911f9 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -105,7 +105,11 @@ Copyright (C) 1986, 1988, 1993-1994, 1996, 1999-2021 Free Software
 \f
 /* Flag which when set indicates a dialog or menu has been posted by
    Xt on behalf of one of the widget sets.  */
+#ifndef HAVE_XINPUT2
 static int popup_activated_flag;
+#else
+int popup_activated_flag;
+#endif
 
 \f
 #ifdef USE_X_TOOLKIT
diff --git a/src/xterm.c b/src/xterm.c
index 961c61c245..41b509449e 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ Copyright (C) 1989, 1993-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ #define XtNinitialState "initialState"
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
 			      const XEvent *, int *,
 			      struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+			      XEvent *, int *,
+			      struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -335,6 +345,156 @@ x_extension_initialize (struct x_display_info *dpyinfo)
   dpyinfo->ext_codes = ext_codes;
 }
 
+
+#ifdef HAVE_XINPUT2
+
+/* Free all XI2 devices on dpyinfo.  */
+static void
+x_free_xi_devices (struct x_display_info *dpyinfo)
+{
+  block_input ();
+
+  if (dpyinfo->num_devices)
+    {
+      for (int i = 0; i < dpyinfo->num_devices; ++i)
+	xfree (dpyinfo->devices[i].valuators);
+
+      xfree (dpyinfo->devices);
+      dpyinfo->devices = NULL;
+      dpyinfo->num_devices = 0;
+    }
+
+  unblock_input ();
+}
+
+/* Setup valuator tracking for XI2 master devices on
+   DPYINFO->display.  */
+
+static void
+x_init_master_valuators (struct x_display_info *dpyinfo)
+{
+  int ndevices;
+  XIDeviceInfo *infos;
+
+  block_input ();
+  x_free_xi_devices (dpyinfo);
+  infos = XIQueryDevice (dpyinfo->display,
+			 XIAllMasterDevices,
+			 &ndevices);
+
+  if (!ndevices)
+    {
+      XIFreeDeviceInfo (infos);
+      unblock_input ();
+      return;
+    }
+
+  int actual_devices = 0;
+  dpyinfo->devices = xmalloc (sizeof *dpyinfo->devices * ndevices);
+
+  for (int i = 0; i < ndevices; ++i)
+    {
+      XIDeviceInfo *device = &infos[i];
+
+      if (device->enabled)
+	{
+	  int actual_valuator_count = 0;
+	  struct xi_device_t *xi_device =
+	    &dpyinfo->devices[actual_devices++];
+	  xi_device->device_id = device->deviceid;
+	  xi_device->valuators =
+	    xmalloc (sizeof *xi_device->valuators * device->num_classes);
+
+	  for (int c = 0; c < device->num_classes; ++c)
+	    {
+	      switch (device->classes[c]->type)
+		{
+#ifdef XIScrollClass /* XInput 2.1 */
+		case XIScrollClass:
+		  {
+		    XIScrollClassInfo *info =
+		      (XIScrollClassInfo *) device->classes[c];
+		    struct xi_scroll_valuator_t *valuator =
+		      &xi_device->valuators[actual_valuator_count++];
+
+		    valuator->horizontal = (info->scroll_type == XIScrollTypeHorizontal);
+		    valuator->invalid_p = true;
+		    valuator->emacs_value = DBL_MIN;
+		    valuator->increment = info->increment;
+		    valuator->number = info->number;
+		    break;
+		  }
+#endif
+		default:
+		  break;
+		}
+	    }
+	  xi_device->scroll_valuator_count = actual_valuator_count;
+	}
+    }
+
+  dpyinfo->num_devices = actual_devices;
+  XIFreeDeviceInfo (infos);
+  unblock_input ();
+}
+
+/* Return the delta of the scroll valuator VALUATOR_NUMBER under
+   DEVICE_ID in the display DPYINFO with VALUE.  The valuator's
+   valuator will be set to VALUE afterwards.  In case no scroll
+   valuator is found, or if device_id is not known to Emacs, DBL_MAX
+   is returned.  Otherwise, the valuator is returned in
+   VALUATOR_RETURN.  */
+static double
+x_get_scroll_valuator_delta (struct x_display_info *dpyinfo, int device_id,
+			     int valuator_number, double value,
+			     struct xi_scroll_valuator_t **valuator_return)
+{
+  block_input ();
+
+  for (int i = 0; i < dpyinfo->num_devices; ++i)
+    {
+      struct xi_device_t *device = &dpyinfo->devices[i];
+
+      if (device->device_id == device_id)
+	{
+	  for (int j = 0; j < device->scroll_valuator_count; ++j)
+	    {
+	      struct xi_scroll_valuator_t *sv = &device->valuators[j];
+
+	      if (sv->number == valuator_number)
+		{
+		  if (sv->invalid_p)
+		    {
+		      sv->current_value = value;
+		      sv->invalid_p = false;
+		      *valuator_return = sv;
+
+		      unblock_input ();
+		      return 0.0;
+		    }
+		  else
+		    {
+		      double delta = sv->current_value - value;
+		      sv->current_value = value;
+		      *valuator_return = sv;
+
+		      unblock_input ();
+		      return delta / sv->increment;
+		    }
+		}
+	    }
+
+	  unblock_input ();
+	  return DBL_MAX;
+	}
+    }
+
+  unblock_input ();
+  return DBL_MAX;
+}
+
+#endif
+
 void
 x_cr_destroy_frame_context (struct frame *f)
 {
@@ -4665,7 +4825,16 @@ x_any_window_to_frame (struct x_display_info *dpyinfo, int wdesc)
 x_menubar_window_to_frame (struct x_display_info *dpyinfo,
 			   const XEvent *event)
 {
-  Window wdesc = event->xany.window;
+  Window wdesc;
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent
+      && dpyinfo->supports_xi2
+      && (event->xcookie.evtype == XI_ButtonPress
+	  || event->xcookie.evtype == XI_ButtonRelease))
+    wdesc = ((XIDeviceEvent *) event->xcookie.data)->event;
+  else
+#endif
+    wdesc = event->xany.window;
   Lisp_Object tail, frame;
   struct frame *f;
   struct x_output *x;
@@ -4768,6 +4937,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+	if (!((xi_event->evtype == XI_Enter
+	       || xi_event->evtype == XI_Leave)
+	      && (focus_state & FOCUS_EXPLICIT)))
+	  x_focus_changed ((xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_FocusIn
+			    ? FocusIn : FocusOut),
+			   (xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_Leave
+			    ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+			   dpyinfo, frame, bufp);
+	break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7872,7 +8064,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
 		   const XEvent *event,
+#else
+		   XEvent *event,
+#endif
 		   int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -7898,7 +8094,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -8365,6 +8568,10 @@ handle_one_xevent (struct x_display_info *dpyinfo,
       goto OTHER;
 
     case MapNotify:
+#if defined HAVE_XINPUT2 && defined HAVE_GTK3
+      if (xg_is_menu_window (dpyinfo->display, event->xmap.window))
+	popup_activated_flag = 1;
+#endif
       /* We use x_top_window_to_frame because map events can
          come for sub-windows and they don't mean that the
          frame is visible.  */
@@ -9343,6 +9550,832 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	if (!dpyinfo->supports_xi2)
+	  goto OTHER;
+	if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+	  /* Not an XI2 event. */
+	  goto OTHER;
+	bool must_free_data = false;
+	XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+	/* Sometimes the event is already claimed by GTK, which
+	   will free its data in due course. */
+	if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+	  {
+	    must_free_data = true;
+	    xi_event = (XIEvent *) event->xcookie.data;
+	  }
+
+	XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+	XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+	XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+	XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+	XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+	XIValuatorState *states;
+	double *values;
+	bool found_valuator = false;
+
+	/* A fake XMotionEvent for x_note_mouse_movement. */
+	XMotionEvent ev;
+	/* A fake XButtonEvent for x_construct_mouse_click. */
+	XButtonEvent bv;
+
+	if (!xi_event)
+	  {
+	    eassert (!must_free_data);
+	    goto OTHER;
+	  }
+
+	switch (event->xcookie.evtype)
+	  {
+	  case XI_FocusIn:
+	    any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+	    /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+	       minimized/iconified windows; thus, for those WMs we won't get
+	       a MapNotify when unminimizing/deconifying.  Check here if we
+	       are deiconizing a window (Bug42655).
+
+	       But don't do that on GTK since it may cause a plain invisible
+	       frame get reported as iconified, compare
+	       https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+	       That is fixed above but bites us here again.  */
+	    f = any;
+	    if (f && FRAME_ICONIFIED_P (f))
+	      {
+		SET_FRAME_VISIBLE (f, 1);
+		SET_FRAME_ICONIFIED (f, false);
+		f->output_data.x->has_been_visible = true;
+		inev.ie.kind = DEICONIFY_EVENT;
+		XSETFRAME (inev.ie.frame_or_window, f);
+	      }
+#endif /* USE_GTK */
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_FocusOut:
+	    any = x_any_window_to_frame (dpyinfo, focusout->event);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_Enter:
+	    any = x_any_window_to_frame (dpyinfo, enter->event);
+	    ev.x = lrint (enter->event_x);
+	    ev.y = lrint (enter->event_y);
+	    ev.window = leave->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    f = any;
+
+	    if (f && x_mouse_click_focus_ignore_position)
+	      ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+	    /* EnterNotify counts as mouse movement,
+	       so update things that depend on mouse position.  */
+	    if (f && !f->output_data.x->hourglass_p)
+	      x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+	    /* We may get an EnterNotify on the buttons in the toolbar.  In that
+	       case we moved out of any highlighted area and need to note this.  */
+	    if (!f && dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Leave:
+	    ev.x = lrint (leave->event_x);
+	    ev.y = lrint (leave->event_y);
+	    ev.window = leave->event;
+	    any = x_any_window_to_frame (dpyinfo, leave->event);
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+
+	    f = x_top_window_to_frame (dpyinfo, leave->event);
+	    if (f)
+	      {
+		if (f == hlinfo->mouse_face_mouse_frame)
+		  {
+		    /* If we move outside the frame, then we're
+		       certainly no longer on any text in the frame.  */
+		    clear_mouse_face (hlinfo);
+		    hlinfo->mouse_face_mouse_frame = 0;
+		  }
+
+		/* Generate a nil HELP_EVENT to cancel a help-echo.
+		   Do it only if there's something to cancel.
+		   Otherwise, the startup message is cleared when
+		   the mouse leaves the frame.  */
+		if (any_help_event_p)
+		  do_help = -1;
+	      }
+#ifdef USE_GTK
+	    /* See comment in EnterNotify above */
+	    else if (dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Motion:
+	    /* First test if there is some kind of scroll event
+	       here! */
+	    states = &xev->valuators;
+	    values = states->values;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+
+	    for (int i = 0; i < states->mask_len * 8; i++)
+	      {
+		if (XIMaskIsSet (states->mask, i))
+		  {
+		    block_input ();
+
+		    struct xi_scroll_valuator_t *val;
+		    double delta =
+		      x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
+						   i, *values, &val);
+
+		    if (delta != DBL_MAX)
+		      {
+			/* TODO: Figure out how pixelwise scrolling should work.
+			   Until that happens, this will have to do.  */
+			delta *= 10;
+
+			f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+			found_valuator = true;
+			if (signbit (delta) != signbit (val->emacs_value))
+			  val->emacs_value = DBL_MIN;
+
+			val->emacs_value += delta;
+
+			if (!f)
+			  {
+			    f = x_any_window_to_frame (dpyinfo, xev->event);
+
+			    if (!f)
+			      {
+				unblock_input ();
+				goto XI_OTHER;
+			      }
+			  }
+
+			if ((val->horizontal
+			     && fabs (val->emacs_value) >= FRAME_COLUMN_WIDTH (f))
+			    || (!val->horizontal
+				&& fabs (val->emacs_value) >= FRAME_LINE_HEIGHT (f)))
+			  {
+			    Lisp_Object tab_bar_arg = Qnil;
+			    bool tab_bar_p = false;
+			    bool tool_bar_p = false;
+			    bool s = signbit (val->emacs_value);
+
+			    bv.button = !val->horizontal ? (s ? 5 : 4) : (s ? 7 : 6);
+			    bv.type = ButtonPress;
+
+			    bv.x = lrint (xev->event_x);
+			    bv.y = lrint (xev->event_y);
+			    bv.window = xev->event;
+			    bv.state = xev->mods.base
+			      | xev->mods.effective
+			      | xev->mods.latched
+			      | xev->mods.locked;
+
+			    /* Is this in the tab-bar?  */
+			    if (WINDOWP (f->tab_bar_window)
+				&& WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+			      {
+				Lisp_Object window;
+				int x = bv.x;
+				int y = bv.y;
+
+				window = window_from_coordinates (f, x, y, 0, true, true);
+				tab_bar_p = EQ (window, f->tab_bar_window);
+
+				if (tab_bar_p)
+				  {
+				    tab_bar_arg = handle_tab_bar_click
+				      (f, x, y, true, x_x_to_emacs_modifiers (dpyinfo, bv.state));
+				    tab_bar_arg = handle_tab_bar_click
+				      (f, x, y, false, x_x_to_emacs_modifiers (dpyinfo, bv.state));
+				  }
+			      }
+
+			    if (!NILP (tab_bar_arg))
+			      inev.ie.arg = tab_bar_arg;
+
+			    if (!tool_bar_p && !(NILP (tab_bar_arg) && tab_bar_p))
+			      {
+				if (ignore_next_mouse_click_timeout)
+				  {
+				    if (xev->time > ignore_next_mouse_click_timeout)
+				      {
+					/* XXX: Wouldn't it be better
+					   to just use wheel events
+					   instead of pretending to be
+					   X here? */
+					x_construct_mouse_click (&inev.ie, &bv, f);
+					if (!NILP (tab_bar_arg))
+					  inev.ie.arg = tab_bar_arg;
+					kbd_buffer_store_event (&inev.ie);
+					inev.ie.modifiers &= ~down_modifier;
+					inev.ie.modifiers |= up_modifier;
+					kbd_buffer_store_event (&inev.ie);
+				      }
+				    ignore_next_mouse_click_timeout = 0;
+				  }
+				else
+				  {
+				    x_construct_mouse_click (&inev.ie, &bv, f);
+				    kbd_buffer_store_event (&inev.ie);
+				    inev.ie.modifiers &= ~down_modifier;
+				    inev.ie.modifiers |= up_modifier;
+				    kbd_buffer_store_event (&inev.ie);
+				  }
+			      }
+
+			    val->emacs_value = DBL_MIN;
+			  }
+		      }
+		    unblock_input ();
+		    values++;
+		  }
+
+		inev.ie.kind = NO_EVENT;
+	      }
+
+	    if (found_valuator)
+	      goto XI_OTHER;
+
+	    ev.x = lrint (xev->event_x);
+	    ev.y = lrint (xev->event_y);
+	    ev.window = xev->event;
+
+	    previous_help_echo_string = help_echo_string;
+	    help_echo_string = Qnil;
+
+	    if (hlinfo->mouse_face_hidden)
+	      {
+		hlinfo->mouse_face_hidden = false;
+		clear_mouse_face (hlinfo);
+	      }
+
+	    f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+	    if (f && xg_event_is_for_scrollbar (f, event))
+	      f = 0;
+#endif
+	    if (f)
+	      {
+		/* Maybe generate a SELECT_WINDOW_EVENT for
+		   `mouse-autoselect-window' but don't let popup menus
+		   interfere with this (Bug#1261).  */
+		if (!NILP (Vmouse_autoselect_window)
+		    && !popup_activated ()
+		    /* Don't switch if we're currently in the minibuffer.
+		       This tries to work around problems where the
+		       minibuffer gets unselected unexpectedly, and where
+		       you then have to move your mouse all the way down to
+		       the minibuffer to select it.  */
+		    && !MINI_WINDOW_P (XWINDOW (selected_window))
+		    /* With `focus-follows-mouse' non-nil create an event
+		       also when the target window is on another frame.  */
+		    && (f == XFRAME (selected_frame)
+			|| !NILP (focus_follows_mouse)))
+		  {
+		    static Lisp_Object last_mouse_window;
+		    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+		    /* A window will be autoselected only when it is not
+		       selected now and the last mouse movement event was
+		       not in it.  The remainder of the code is a bit vague
+		       wrt what a "window" is.  For immediate autoselection,
+		       the window is usually the entire window but for GTK
+		       where the scroll bars don't count.  For delayed
+		       autoselection the window is usually the window's text
+		       area including the margins.  */
+		    if (WINDOWP (window)
+			&& !EQ (window, last_mouse_window)
+			&& !EQ (window, selected_window))
+		      {
+			inev.ie.kind = SELECT_WINDOW_EVENT;
+			inev.ie.frame_or_window = window;
+		      }
+
+		    /* Remember the last window where we saw the mouse.  */
+		    last_mouse_window = window;
+		  }
+
+		if (!x_note_mouse_movement (f, &ev))
+		  help_echo_string = previous_help_echo_string;
+	      }
+	    else
+	      {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+		struct scroll_bar *bar
+		  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+		if (bar)
+		  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+		/* If we move outside the frame, then we're
+		   certainly no longer on any text in the frame.  */
+		clear_mouse_face (hlinfo);
+	      }
+
+	    /* If the contents of the global variable help_echo_string
+	       has changed, generate a HELP_EVENT.  */
+	    if (!NILP (help_echo_string)
+		|| !NILP (previous_help_echo_string))
+	      do_help = 1;
+	    goto XI_OTHER;
+	  case XI_ButtonRelease:
+	  case XI_ButtonPress:
+	    {
+	      /* If we decide we want to generate an event to be seen
+		 by the rest of Emacs, we put it here.  */
+	      Lisp_Object tab_bar_arg = Qnil;
+	      bool tab_bar_p = false;
+	      bool tool_bar_p = false;
+
+	      /* Ignore emulated scroll events when XI2 native
+		 scroll events are present.  */
+	      if (dpyinfo->xi2_version >= 1 && xev->detail >= 4
+		  && xev->detail <= 8)
+		goto XI_OTHER;
+
+	      bv.button = xev->detail;
+	      bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+	      bv.x = lrint (xev->event_x);
+	      bv.y = lrint (xev->event_y);
+	      bv.window = xev->event;
+	      bv.state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+
+	      memset (&compose_status, 0, sizeof (compose_status));
+	      dpyinfo->last_mouse_glyph_frame = NULL;
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+
+	      f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+	      if (f && xev->evtype == XI_ButtonPress
+		  && !popup_activated ()
+		  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+		  && !FRAME_NO_ACCEPT_FOCUS (f))
+		{
+		  /* When clicking into a child frame or when clicking
+		     into a parent frame with the child frame selected and
+		     `no-accept-focus' is not set, select the clicked
+		     frame.  */
+		  struct frame *hf = dpyinfo->highlight_frame;
+
+		  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+		    {
+		      block_input ();
+		      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+				      RevertToParent, CurrentTime);
+		      if (FRAME_PARENT_FRAME (f))
+			XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+		      unblock_input ();
+		    }
+		}
+
+#ifdef USE_GTK
+	      if (f && xg_event_is_for_scrollbar (f, event))
+		f = 0;
+#endif
+
+	      if (f)
+		{
+		  /* Is this in the tab-bar?  */
+		  if (WINDOWP (f->tab_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tab_bar_p = EQ (window, f->tab_bar_window);
+
+		      if (tab_bar_p)
+			tab_bar_arg = handle_tab_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+
+#if ! defined (USE_GTK)
+		  /* Is this in the tool-bar?  */
+		  if (WINDOWP (f->tool_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tool_bar_p = EQ (window, f->tool_bar_window);
+
+		      if (tool_bar_p && xev->detail < 4)
+			handle_tool_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+#endif /* !USE_GTK */
+
+		  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+		    if (! popup_activated ())
+#endif
+		      {
+			if (ignore_next_mouse_click_timeout)
+			  {
+			    if (xev->evtype == XI_ButtonPress
+				&& xev->time > ignore_next_mouse_click_timeout)
+			      {
+				ignore_next_mouse_click_timeout = 0;
+				x_construct_mouse_click (&inev.ie, &bv, f);
+			      }
+			    if (xev->evtype == XI_ButtonRelease)
+			      ignore_next_mouse_click_timeout = 0;
+			  }
+			else
+			  x_construct_mouse_click (&inev.ie, &bv, f);
+
+			if (!NILP (tab_bar_arg))
+			  inev.ie.arg = tab_bar_arg;
+		      }
+		  if (FRAME_X_EMBEDDED_P (f))
+		    xembed_send_message (f, xev->time,
+					 XEMBED_REQUEST_FOCUS, 0, 0, 0);
+		}
+
+	      if (xev->evtype == XI_ButtonPress)
+		{
+		  dpyinfo->grabbed |= (1 << xev->detail);
+		  dpyinfo->last_mouse_frame = f;
+		  if (f && !tab_bar_p)
+		    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+		  if (f && !tool_bar_p)
+		    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+		}
+	      else
+		dpyinfo->grabbed &= ~(1 << xev->detail);
+
+	      if (f)
+		f->mouse_moved = false;
+
+#if defined (USE_GTK)
+	      /* No Xt toolkit currently available has support for XI2.
+	         So the code here assumes use of GTK.  */
+	      f = x_menubar_window_to_frame (dpyinfo, event);
+	      if (f /* Gtk+ menus only react to the first three buttons. */
+		  && xev->detail < 3)
+		{
+		  /* What is done with Core Input ButtonPressed is not
+		     possible here, because GenericEvents cannot be saved.  */
+		  bool was_waiting_for_input = waiting_for_input;
+		  /* This hack was adopted from the NS port.  Whether
+		     or not it is actually safe is a different story
+		     altogether.  */
+		  if (waiting_for_input)
+		    waiting_for_input = 0;
+		  set_frame_menubar (f, true);
+		  waiting_for_input = was_waiting_for_input;
+		}
+#endif
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyPress:
+	    {
+	      int state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+	      Lisp_Object c;
+#ifdef HAVE_XKB
+	      unsigned int mods_rtrn;
+#endif
+	      int keycode = xev->detail;
+	      KeySym keysym;
+	      char copy_buffer[81];
+	      char *copy_bufptr = copy_buffer;
+	      unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+	      int copy_bufsiz = sizeof (copy_buffer);
+#endif
+	      ptrdiff_t i;
+	      int nchars, len;
+
+#ifdef HAVE_XKB
+	      if (dpyinfo->xkb_desc)
+		{
+		  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+					    state, &mods_rtrn, &keysym))
+		    goto XI_OTHER;
+		}
+	      else
+		{
+#endif
+		  int keysyms_per_keycode_return;
+		  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+						      &keysyms_per_keycode_return);
+		  if (!(keysym = ksms[0]))
+		    {
+		      XFree (ksms);
+		      goto XI_OTHER;
+		    }
+		  XFree (ksms);
+#ifdef HAVE_XKB
+		}
+#endif
+
+	      if (keysym == NoSymbol)
+		goto XI_OTHER;
+
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+	      ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+	      /* Dispatch XI_KeyPress events when in menu.  */
+	      if (popup_activated ())
+		goto XI_OTHER;
+#endif
+
+	      f = x_any_window_to_frame (dpyinfo, xev->event);
+
+	      /* If mouse-highlight is an integer, input clears out
+		 mouse highlighting.  */
+	      if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+		  && (f == 0
+#if ! defined (USE_GTK)
+		      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+		      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+		  )
+		{
+		  clear_mouse_face (hlinfo);
+		  hlinfo->mouse_face_hidden = true;
+		}
+
+	      if (f != 0)
+		{
+#ifdef USE_GTK
+		  /* Don't pass keys to GTK.  A Tab will shift focus to the
+		     tool bar in GTK 2.4.  Keys will still go to menus and
+		     dialogs because in that case popup_activated is nonzero
+		     (see above).  */
+		  *finish = X_EVENT_DROP;
+#endif
+		  /* If not using XIM/XIC, and a compose sequence is in progress,
+		     we break here.  Otherwise, chars_matched is always 0.  */
+		  if (compose_status.chars_matched > 0 && nbytes == 0)
+		    goto XI_OTHER;
+
+		  memset (&compose_status, 0, sizeof (compose_status));
+
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  inev.ie.modifiers
+		    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+		  inev.ie.timestamp = xev->time;
+
+		  /* First deal with keysyms which have defined
+		     translations to characters.  */
+		  if (keysym >= 32 && keysym < 128)
+		    /* Avoid explicitly decoding each ASCII character.  */
+		    {
+		      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+
+		      goto xi_done_keysym;
+		    }
+
+		  /* Keysyms directly mapped to Unicode characters.  */
+		  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+		    {
+		      if (keysym < 0x01000080)
+			inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      else
+			inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym & 0xFFFFFF;
+		      goto xi_done_keysym;
+		    }
+
+		  /* Now non-ASCII.  */
+		  if (HASH_TABLE_P (Vx_keysym_table)
+		      && (c = Fgethash (make_fixnum (keysym),
+					Vx_keysym_table,
+					Qnil),
+			  FIXNATP (c)))
+		    {
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = XFIXNAT (c);
+		      goto xi_done_keysym;
+		    }
+
+		  /* Random non-modifier sorts of keysyms.  */
+		  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+		       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+		       || (keysym >= XK_ISO_Left_Tab
+			   && keysym <= XK_ISO_Enter)
+#endif
+		       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+		       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+		       /* This recognizes the "extended function
+			  keys".  It seems there's no cleaner way.
+			  Test IsModifierKey to avoid handling
+			  mode_switch incorrectly.  */
+		       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+		       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+		       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+		       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+		       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+		       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+		       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+		       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+		       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+		       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+		       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+		       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+		       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+		       || keysym == XK_dead_abovedot
+#endif
+		       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+		       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+		       /* Any "vendor-specific" key is ok.  */
+		       || (keysym & (1 << 28))
+		       || (keysym != NoSymbol && nbytes == 0))
+		      && ! (IsModifierKey (keysym)
+			    /* The symbols from XK_ISO_Lock
+			       to XK_ISO_Last_Group_Lock
+			       don't have real modifiers but
+			       should be treated similarly to
+			       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+			    || (XK_ISO_Lock <= keysym
+				&& keysym <= XK_ISO_Last_Group_Lock)
+#endif
+			    ))
+		    {
+		      STORE_KEYSYM_FOR_DEBUG (keysym);
+		      /* make_lispy_event will convert this to a symbolic
+			 key.  */
+		      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+		      goto xi_done_keysym;
+		    }
+
+#ifdef HAVE_XKB
+		  int overflow = 0;
+		  KeySym sym = keysym;
+
+		  if (dpyinfo->xkb_desc)
+		    {
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz, &overflow)))
+			goto XI_OTHER;
+		    }
+		  else
+#else
+		    {
+		      block_input ();
+		      char *str = XKeysymToString (keysym);
+		      if (!str)
+			{
+			  unblock_input ();
+			  goto XI_OTHER;
+			}
+		      nbytes = strlen (str) + 1;
+		      copy_bufptr = alloca (nbytes);
+		      strcpy (copy_bufptr, str);
+		      unblock_input ();
+		    }
+#endif
+#ifdef HAVE_XKB
+		  if (overflow)
+		    {
+		      overflow = 0;
+		      copy_bufptr = alloca (copy_bufsiz + overflow);
+		      keysym = sym;
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz + overflow, &overflow)))
+			goto XI_OTHER;
+
+		      if (overflow)
+			goto XI_OTHER;
+		    }
+#endif
+
+		  for (i = 0, nchars = 0; i < nbytes; i++)
+		    {
+		      if (ASCII_CHAR_P (copy_bufptr[i]))
+			nchars++;
+		      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+		    }
+
+		  if (nchars < nbytes)
+		    {
+		      /* Decode the input data.  */
+
+		      setup_coding_system (Vlocale_coding_system, &coding);
+		      coding.src_multibyte = false;
+		      coding.dst_multibyte = true;
+		      /* The input is converted to events, thus we can't
+			 handle composition.  Anyway, there's no XIM that
+			 gives us composition information.  */
+		      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+		      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+				    nbytes);
+		      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+		      coding.mode |= CODING_MODE_LAST_BLOCK;
+		      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr, nbytes, Qnil);
+		      nbytes = coding.produced;
+		      nchars = coding.produced_char;
+		      copy_bufptr = (char *) coding.destination;
+		    }
+
+		  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+		  /* Convert the input data to a sequence of
+		     character events.  */
+		  for (i = 0; i < nbytes; i += len)
+		    {
+		      int ch;
+		      if (nchars == nbytes)
+			ch = copy_ubufptr[i], len = 1;
+		      else
+			ch = string_char_and_length (copy_ubufptr + i, &len);
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = ch;
+		      kbd_buffer_store_buffered_event (&inev, hold_quit);
+		    }
+
+		  inev.ie.kind = NO_EVENT;
+		  goto xi_done_keysym;
+		}
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyRelease:
+	    x_display_set_last_user_time (dpyinfo, xev->time);
+	    goto XI_OTHER;
+	  case XI_PropertyEvent:
+	  case XI_HierarchyChanged:
+	  case XI_DeviceChanged:
+	    x_init_master_valuators (dpyinfo);
+	    goto XI_OTHER;
+	  default:
+	    goto XI_OTHER;
+	  }
+      xi_done_keysym:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto done_keysym;
+      XI_OTHER:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13013,6 +14046,40 @@ #define NUM_ARGV 10
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#elif defined XIScrollClass /* XInput 1.1 */
+  int minor = 1;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+		       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+	{
+	  dpyinfo->supports_xi2 = true;
+	  x_init_master_valuators (dpyinfo);
+	}
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+				 XkbAllComponentsMask,
+				 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13445,6 +14512,14 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+	XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
+#ifdef HAVE_XINPUT2
+      if (dpyinfo->supports_xi2)
+	x_free_xi_devices (dpyinfo);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13604,9 +14679,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index de6ea50385..46238333a9 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ #define XSync(d, b) do { gdk_window_process_all_updates (); \
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -163,6 +167,26 @@ #define MAX_CLIP_RECTS 2
   char *name;
 };
 
+#ifdef HAVE_XINPUT2
+struct xi_scroll_valuator_t
+{
+  bool invalid_p;
+  double current_value;
+  double emacs_value;
+  double increment;
+
+  int number;
+  int horizontal;
+};
+
+struct xi_device_t
+{
+  int device_id;
+  int scroll_valuator_count;
+  struct xi_scroll_valuator_t *valuators;
+};
+#endif
+
 Status x_parse_color (struct frame *f, const char *color_name,
 		      XColor *color);
 
@@ -474,6 +498,19 @@ #define MAX_CLIP_RECTS 2
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+
+  int num_devices;
+  struct xi_device_t *devices;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
@@ -481,6 +518,11 @@ #define MAX_CLIP_RECTS 2
 extern bool use_xim;
 #endif
 
+#ifdef HAVE_XINPUT2
+/* Defined in xmenu.c. */
+extern int popup_activated_flag;
+#endif
+
 /* This is a chain of structures for all the X displays currently in use.  */
 extern struct x_display_info *x_display_list;
 
-- 
2.31.1


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A pain point with this code is how the Lisp-side mwheel code assumes
that the wheel event will always be mouse-4 to 8 under X, so the code
tries to emulate the legacy Core Input behaviour instead of generating
WHEEL_EVENTs.  To properly support XInput 2 scrolling, mwheel.el will
have to be modified to support using both kinds of events under the same
session.