Re: "Final" version of tty child frames

[martin rudalics <rudalics@gmx.at>]

 >> If you have the time, please also try to look into two issues I raised
 >> earlier:
 >>
 >>   Two further things I noticed: When point in the parent frame is
 >>   effectively hidden by the child frame, its cursor sometimes appears at
 >>   the right of the child frame and sometimes it's not shown.  I have not
 >>   understood the underlying principle for this behavior.  Also when the
 >>   selected region in the parent frame is active, its overlay covers the
 >>   child frame.  That's ugly.
 >
 > TTY child frame cursors behave even worse under GPM and a TERM=linux
 > terminal.  In this case, the cursor ends up on some lines always
 > appearing at the end of lines (ignoring separate frames or windows)
 > and sometimes in the right place.  The point position is correct
 > though and the cursor does appear correctly once I start pressing
 > simple keys like 'A'.

Both issues I raised above seem to be gone with master I pulled today.
Thanks for fixing them.

One thing I noticed is that with code like the following

(defvar tty-child-frame nil)
(defvar tty-child-buffer (get-buffer-create "*tty-child-buffer*"))
(defvar tty-child-window nil)

(defun tty-make-child-frame ()
   (interactive)
   (setq tty-child-frame
	(make-frame
	 `((parent-frame . ,(selected-frame))
	   (left . 20)
	   (top . 10)
	   (width . 0.3)
	   (height . 0.8)
	   (border-width . 0)
	   (background-color . "yellow")
	   (tool-bar-lines . 0)
	   (menu-bar-lines . 0)
	   (minibuffer . nil)
	   (no-special-glyphs . t)
	   )))
   (setq tty-child-window (frame-root-window tty-child-frame))
   (set-window-buffer tty-child-window tty-child-buffer)
   (set-face-background 'internal-border "blue" tty-child-frame)
   (set-face-background 'child-frame-border "blue" tty-child-frame))

(defun tty-toggle-child-frame ()
   (interactive)
   (if (frame-live-p tty-child-frame)
       (if (frame-visible-p tty-child-frame)
	  (make-frame-invisible tty-child-frame)
	(make-frame-visible tty-child-frame))
     (tty-make-child-frame)))

(defun tty-switch-to-child-frame ()
   (interactive)
   (if (frame-live-p tty-child-frame)
       (if (frame-visible-p tty-child-frame)
	  (if (eq tty-child-frame (selected-frame))
	      (select-frame-set-input-focus (frame-parent tty-child-frame))
	    (select-frame-set-input-focus tty-child-frame))
	(make-frame-visible tty-child-frame)
	(select-frame-set-input-focus tty-child-frame))
     (tty-make-child-frame)
     (select-frame-set-input-focus tty-child-frame)))

then when I first evaluate 'tty-toggle-child-frame' followed by
'tty-switch-to-child-frame' and I start typing I get an assertion
failure with a backtrace like the below

#0  terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at ../../src/emacs.c:432
#1  0x0000000000699b76 in die (msg=0x7dfc63 "FRAME_VISIBLE_P (root)", file=0x7df29f "../../src/dispnew.c", line=3962) at ../../src/alloc.c:8059
#2  0x0000000000427575 in combine_updates_for_frame (f=0x18662e0, inhibit_scrolling=false) at ../../src/dispnew.c:3962
#3  0x00000000004832fc in redisplay_internal () at ../../src/xdisp.c:17699
#4  0x0000000000483719 in redisplay_preserve_echo_area (from_where=8) at ../../src/xdisp.c:17835
#5  0x000000000060b715 in detect_input_pending_run_timers (do_display=true) at ../../src/keyboard.c:11579
#6  0x00000000007465d9 in wait_reading_process_output (time_limit=30, nsecs=0, read_kbd=-1, do_display=true, wait_for_cell=XIL(0), wait_proc=0x0, just_wait_proc=0) at ../../src/process.c:5856
#7  0x0000000000430243 in sit_for (timeout=make_fixnum(30), reading=true, display_option=1) at ../../src/dispnew.c:6889
#8  0x00000000005f6383 in read_char (commandflag=1, map=XIL(0x7ff1fcdf4053), prev_event=XIL(0), used_mouse_menu=0x7ffc85a5703f, end_time=0x0) at ../../src/keyboard.c:2925
#9  0x00000000006097f3 in read_key_sequence (keybuf=0x7ffc85a571f0, prompt=XIL(0), dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true, prevent_redisplay=false, disable_text_conversion_p=false) at ../../src/keyboard.c:10746
#10 0x00000000005f1c46 in command_loop_1 () at ../../src/keyboard.c:1424
#11 0x00000000006d06e3 in internal_condition_case (bfun=0x5f1817 <command_loop_1>, handlers=XIL(0x90), hfun=0x5f0c99 <cmd_error>) at ../../src/eval.c:1607
#12 0x00000000005f13de in command_loop_2 (handlers=XIL(0x90)) at ../../src/keyboard.c:1163
#13 0x00000000006cfb39 in internal_catch (tag=XIL(0x122d0), func=0x5f13b4 <command_loop_2>, arg=XIL(0x90)) at ../../src/eval.c:1286
#14 0x00000000005f1370 in command_loop () at ../../src/keyboard.c:1141
#15 0x00000000005f073b in recursive_edit_1 () at ../../src/keyboard.c:749
#16 0x00000000005f0967 in Frecursive_edit () at ../../src/keyboard.c:832
#17 0x00000000005ec1cd in main (argc=5, argv=0x7ffc85a57828) at ../../src/emacs.c:2636

Lisp Backtrace:
"redisplay_internal (C function)" (0x0)

The cause is that my 'tty-make-child-frame' has

	 `((parent-frame . ,(selected-frame))
...
	   (minibuffer . nil)

but the consequences are completely unclear to me.  What happens is that
make_terminal_frame has this

	  if (EQ (mini, Qnone) || NILP (mini))
	    f = make_frame_without_minibuffer (Qnil, kb, Qnil);

which reenters make_terminal_frame and does

       if (FRAME_LIVE_P (root))
	SET_FRAME_VISIBLE (root, false);

for the old selected "root" frame.

What's the purpose of creating a new top frame without minibuffer here?
We end up with three frames - the initial one, the child frame and the
new root frame without minibuffer.  redisplay_internal eventually
detects here

       Lisp_Object mini_window = FRAME_MINIBUF_WINDOW (sf);
       struct frame *mini_frame = XFRAME (WINDOW_FRAME (XWINDOW (mini_window)));

       if (mini_frame != sf)

that the mini_frame is not the selected frame

	{
	  XWINDOW (mini_window)->must_be_updated_p = true;
	  update_frame (mini_frame, false);
	  if (is_tty_frame (mini_frame))
	    combine_updates_for_frame (mini_frame, false);

and the call here crashes because mini_frame is the old root frame but
that frame's visibility has been set to false by the code above.

martin