bug#30399: 27.0.50; tooltips are broken

[martin rudalics <rudalics@gmx.at>]

[-- Attachment #1: Type: text/plain, Size: 2108 bytes --]

 > And here's the buggy behavior (starting with step 2) I see on master
 > since the above commit:
 >
 > 0. emacs -Q
 > 1. evaluate (tooltip-show "This is a test")
 >     => A GTK+-themed tooltip is displayed for 10 seconds or until there
 >     is an input event, then disappears.
 > 2. evaluate (x-show-tip "This is a test")
 >     => A GTK+-themed tooltip is displayed and remains displayed, even if
 >     there are input events, until executing step 3 or repeating step 1.

This is due to a rather silly omission which should have already
defeated a feature in Emacs 26 when calling 'x-show-tip' (you've been
warned - Lisp code should call 'tooltip-show').

 > 3. evaluate (let (x-gtk-use-system-tooltips)
 >                (tooltip-show "This is a test"))
 >     => A non-toolkit tooltip is displayed and remains displayed, even if
 >     there are input events, until the end of the Emacs session (at least
 >     I haven't found a way to get rid of it); however, if the GTK+-themed
 >     tooltip from step 2 is still displayed when the above sexp is
 >     evaluated, then after 10 (not 5) seconds the GTK+-themed tooltip
 >     disappears (but the non-toolkit tooltip remains).
 > 4. evaluate (let (x-gtk-use-system-tooltips)
 >                (x-show-tip "This is a test"))
 >     => A non-toolkit tooltip is displayed and remains displayed, even if
 >     there are input events, until the end of the Emacs session AFAICT; if
 >     the tooltip from step 3 is still displayed when the above sexp is
 >     evaluated, it is just moved by this step but does not disappear, and
 >     if the GTK+-themed tooltip from step 2 is still displayed that
 >     tooltip also remains displayed (unlike in step 3).

Let-binding 'x-gtk-use-system-tooltips' is a more delicate issue.  As
a rule, options should never be let-bound but since the customizer is
always right we'll probably have to fix this as well.

Please try the attached fix.  And please test it also with the inverse
scenario

(setq x-gtk-use-system-tooltips nil)
(let ((x-gtk-use-system-tooltips t))
   (tooltip-show "Test"))

Thanks, martin

[-- Attachment #2: gtk-tooltip.diff --]
[-- Type: text/plain, Size: 3955 bytes --]

diff --git a/src/xfns.c b/src/xfns.c
index db1ce31..9f0d946 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -6077,7 +6077,7 @@ static void compute_tip_xy (struct frame *, Lisp_Object, Lisp_Object,
 /* STRING argument of last `x-show-tip' call.  */
 static Lisp_Object tip_last_string;
 
-/* FRAME argument of last `x-show-tip' call.  */
+/* Normalized FRAME argument of last `x-show-tip' call.  */
 static Lisp_Object tip_last_frame;
 
 /* PARMS argument of last `x-show-tip' call.  */
@@ -6542,16 +6542,20 @@ static void compute_tip_xy (struct frame *, Lisp_Object, Lisp_Object,
     }
 
 #ifdef USE_GTK
-  /* The GTK+ system tooltip window can be found via the x_output
-     structure of tip_last_frame, if it still exists.  */
-  if (x_gtk_use_system_tooltips && NILP (tip_last_frame))
-    return Qnil;
-  else if (!x_gtk_use_system_tooltips
-	   && (NILP (tip_frame)
-	       || (!delete
-		   && FRAMEP (tip_frame)
-		   && FRAME_LIVE_P (XFRAME (tip_frame))
-		   && !FRAME_VISIBLE_P (XFRAME (tip_frame)))))
+  /* Any GTK+ system tooltip can be found via the x_output structure of
+     tip_last_frame, provided that frame is still live.  Any Emacs
+     tooltip is found via the tip_frame variable.  Note that the current
+     value of x_gtk_use_system_tooltips might not be the same as used
+     for the tooltip we have to hide, see Bug#30399.  */
+  if ((NILP (tip_last_frame) && NILP (tip_frame))
+      || (!x_gtk_use_system_tooltips
+	  && !delete
+	  && FRAMEP (tip_frame)
+	  && FRAME_LIVE_P (XFRAME (tip_frame))
+	  && !FRAME_VISIBLE_P (XFRAME (tip_frame))))
+    /* Either there's no tooltip to hide or it's an already invisible
+       Emacs tooltip and we don't want to change its type.  Return
+       quickly.  */
     return Qnil;
   else
     {
@@ -6562,10 +6566,9 @@ static void compute_tip_xy (struct frame *, Lisp_Object, Lisp_Object,
       specbind (Qinhibit_redisplay, Qt);
       specbind (Qinhibit_quit, Qt);
 
-      if (x_gtk_use_system_tooltips)
+      /* Try to hide the GTK+ system tip first.  */
+      if (FRAMEP (tip_last_frame))
 	{
-	  /* The GTK+ system tooltip window is stored in the x_output
-	     structure of tip_last_frame.  */
 	  struct frame *f = XFRAME (tip_last_frame);
 
 	  if (FRAME_LIVE_P (f))
@@ -6573,33 +6576,37 @@ static void compute_tip_xy (struct frame *, Lisp_Object, Lisp_Object,
 	      if (xg_hide_tooltip (f))
 		was_open = Qt;
 	    }
-	  else
-	    tip_last_frame = Qnil;
 	}
-      else
+
+      /* Reset tip_last_frame, it will be reassigned when showing the
+	 next GTK+ system tooltip.  */
+      tip_last_frame = Qnil;
+
+      /* Now look whether there's an Emacs tip around.  */
+      if (FRAMEP (tip_frame))
 	{
-	  if (FRAMEP (tip_frame))
-	    {
-	      struct frame *f = XFRAME (tip_frame);
+	  struct frame *f = XFRAME (tip_frame);
 
-	      if (FRAME_LIVE_P (f))
+	  if (FRAME_LIVE_P (f))
+	    {
+	      if (delete || x_gtk_use_system_tooltips)
 		{
-		  if (delete)
-		    {
-		      delete_frame (tip_frame, Qnil);
-		      tip_frame = Qnil;
-		    }
-		  else
-		    x_make_frame_invisible (f);
-
-		  was_open = Qt;
+		  /* Delete the Emacs tooltip frame when DELETE is true
+		     or we change the tooltip type from an Emacs one to
+		     a GTK+ system one.  */
+		  delete_frame (tip_frame, Qnil);
+		  tip_frame = Qnil;
 		}
 	      else
-		tip_frame = Qnil;
+		x_make_frame_invisible (f);
+
+	      was_open = Qt;
 	    }
 	  else
 	    tip_frame = Qnil;
 	}
+      else
+	tip_frame = Qnil;
 
       return unbind_to (count, was_open);
     }
@@ -6721,7 +6728,10 @@ with offset DY added (default is -10).
   if (SCHARS (string) == 0)
     string = make_unibyte_string (" ", 1);
 
+  if (NILP (frame))
+    frame = selected_frame;
   f = decode_window_system_frame (frame);
+
   if (NILP (timeout))
     timeout = make_number (5);
   else