bug#32002: 24.4; Scroll bar start, end not correct

[Mike Kupfer <mkupfer@alum.berkeley.edu>]

[-- Attachment #1: Type: text/plain, Size: 1311 bytes --]

martin rudalics wrote:

> We first have to make sure that you indeed click on the stepper
> buttons.  For this purpose please do the following with Emacs -Q:
> Evaluate
> 
> M-: (setq window-min-height 1) RET
> C-x 2
> M-: (window-resize nil (- 2 (window-height))) RET
> 
> This should get you a one-line window on top of the frame.  Here this
> window has just two small stepper buttons and no slider.  Hopefully,
> yours is the same.

Unfortunately, not.  I initially get whitespace where the scrollbar
should be.  If I change the theme a few times, I eventually get stepper
buttons, but the slider is included, and it all extends down into the
second window (see attached).  (This is with the emacs-26 branch, built
July 4.)

> Now please tell us what clicking or pressing such a button produces.
> If running this under GDB reveals that in xg_scroll_callback 'scroll'
> equals GTK_SCROLL_JUMP, then please tell us the values of 'whole' and
> 'value' in that case.

I've attached 2 logs from the gdb session.  The first was after using
your original instructions.  The second was from using (- 3 ...) instead
of (- 2 ...).  (In the second case the scrollbar was visible, but again
it extended into the lower window.)

Let me know if I messed something up or there is additional data you
need.

thanks,
mike


[-- Attachment #2: Emacs with scrollbar --]
[-- Type: image/png, Size: 44382 bytes --]

[-- Attachment #3: gdb log, original instructions --]
[-- Type: text/plain, Size: 2911 bytes --]

stretch$ gdb /usr/new/bin/emacs
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/new/bin/emacs...done.
(gdb) break xg_scroll_callback
Breakpoint 1 at 0x4be140: file xterm.c, line 5644.
(gdb) run -Q
Starting program: /usr/new/bin/emacs -Q
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe8636700 (LWP 1991)]
[New Thread 0x7fffe6748700 (LWP 1992)]
[New Thread 0x7fffe5d3a700 (LWP 1993)]

Thread 1 "emacs" hit Breakpoint 1, xg_scroll_callback (range=0x2f006f0, 
    scroll=GTK_SCROLL_JUMP, value=7069105, 
    user_data=0x1493c30 <bss_sbrk_buffer+8990864>) at xterm.c:5644
5644	{
(gdb) print *range
$1 = {widget = {parent_instance = {g_type_instance = {g_class = 0x2e20400}, 
      ref_count = 3, qdata = 0x344fd10}, priv = 0x2f00600}, priv = 0x2f00520}
(gdb) next
5648	  GtkAdjustment *adj = GTK_ADJUSTMENT (gtk_range_get_adjustment (range));
(gdb) next
5649	  struct frame *f = g_object_get_data (G_OBJECT (range), XG_FRAME_DATA);
(gdb) next
5648	  GtkAdjustment *adj = GTK_ADJUSTMENT (gtk_range_get_adjustment (range));
(gdb) next
5649	  struct frame *f = g_object_get_data (G_OBJECT (range), XG_FRAME_DATA);
(gdb) print adj
$2 = (GtkAdjustment *) 0x2fc9c80
(gdb) print *adj
$3 = {parent_instance = {g_type_instance = {g_class = 0x2cde5e0}, 
    ref_count = 1, qdata = 0x0}, priv = 0x2fc9c10}
(gdb) next
5651	  if (xg_ignore_gtk_scrollbar) return false;
(gdb) next
5653	  switch (scroll)
(gdb) next
5657	      if (FRAME_DISPLAY_INFO (f)->grabbed != 0
(gdb) next
5660		  if (bar->horizontal)
(gdb) next
5663		      whole = (int)(gtk_adjustment_get_upper (adj) -
(gdb) print whole
$4 = 0
(gdb) next
5660		  if (bar->horizontal)
(gdb) print whole
$5 = 0
(gdb) next
5671		      whole = gtk_adjustment_get_upper (adj) -
(gdb) next
5672			gtk_adjustment_get_page_size (adj);
(gdb) next
5671		      whole = gtk_adjustment_get_upper (adj) -
(gdb) next
5672			gtk_adjustment_get_page_size (adj);
(gdb) next
5673		      portion = min ((int)value, whole);
(gdb) print whole
$6 = 0
(gdb) print gtk_adjustment_get_upper(adj)
$7 = 50109456
(gdb) print gtk_adjustment_get_page_size(adj)
$8 = 50109456
(gdb) cont
Continuing.

[-- Attachment #4: gdb log (- 3 ...) --]
[-- Type: text/plain, Size: 833 bytes --]

Thread 1 "emacs" hit Breakpoint 1, xg_scroll_callback (range=0x2f58750, 
    scroll=GTK_SCROLL_JUMP, value=6164892.9000000004, 
    user_data=0x1493c30 <bss_sbrk_buffer+8990864>) at xterm.c:5644
5644	{
(gdb) next
5648	  GtkAdjustment *adj = GTK_ADJUSTMENT (gtk_range_get_adjustment (range));
(gdb) next
5649	  struct frame *f = g_object_get_data (G_OBJECT (range), XG_FRAME_DATA);
(gdb) print gtk_adjustment_get_upper(adj)
value has been optimized out
(gdb) next
5648	  GtkAdjustment *adj = GTK_ADJUSTMENT (gtk_range_get_adjustment (range));
(gdb) next
5649	  struct frame *f = g_object_get_data (G_OBJECT (range), XG_FRAME_DATA);
(gdb) next
5651	  if (xg_ignore_gtk_scrollbar) return false;
(gdb) print gtk_adjustment_get_upper(adj)
$9 = 49781840
(gdb) print gtk_adjustment_get_page_size(adj)
$10 = 49781840
(gdb) cont
Continuing.