bug#19300: 24.4.51; visual-line-mode messes up after-string rendering when it spans all window columns

[Dmitry Gutov <dgutov@yandex.ru>]

On 12/08/2014 10:39 PM, Eli Zaretskii wrote:
> I meant a recipe to show one window with the problem and another
> without, in the same session.  If you achieve that with the same
> resizing of a window, it'd be interesting to see.

The recipe won't work on your system anyway, right? Since you can't 
reproduce the situation of just "one window with a problem", and the 
above would be a (tiny bit) more complicated version of it.

I can make a video, if you like.

> The pixel size of the canonical character of that font, as you get in
> your session, would be a good start.  E.g., put a breakpoint in
> set_cursor_from_row, then step a few lines, and type "pgrow".
>
> Here's the full recipe:
> ...
>    (gdb) pgrow

Thanks, here's the full output:

Breakpoint 3, Fredraw_display () at dispnew.c:3026
3026	  FOR_EACH_FRAME (tail, frame)
(gdb) break set_cursor_from_row
Breakpoint 4 at 0x42ee50: file xdisp.c, line 14350.
(gdb) continue
Continuing.

Breakpoint 4, set_cursor_from_row (w=0x1170530, row=row@entry=0x159d3c0, 
delta=delta@entry=0, delta_bytes=delta_bytes@entry=0, dy=dy@entry=0, 
dvpos=dvpos@entry=0, matrix=<optimized out>) at xdisp.c:14350
14350	set_cursor_from_row (struct window *w, struct glyph_row *row,
(gdb) continue
Continuing.

Breakpoint 4, set_cursor_from_row (w=0x116f520, row=row@entry=0x18b5230, 
delta=delta@entry=0, delta_bytes=delta_bytes@entry=0, dy=dy@entry=0, 
dvpos=dvpos@entry=0, matrix=<optimized out>) at xdisp.c:14350
14350	set_cursor_from_row (struct window *w, struct glyph_row *row,
(gdb) next
14389	  if (row->mode_line_p)
(gdb) next
14361	  ptrdiff_t pt_old = PT - delta;
(gdb) next
14350	set_cursor_from_row (struct window *w, struct glyph_row *row,
(gdb) pgrow
TEXT: 39 glyphs
   0    0: STRETCH[20+15] pos=740 w=64 a+d=15+5 MB
   1   64: STRETCH[20+15] pos=741 w=64 a+d=15+5 MB
   2  128: STRETCH[20+15] pos=742 w=64 a+d=15+5 MB
   3  192: CHAR[ ] pos=743 blev=0,btyp=L w=8 a+d=15+5 MB
   4  200: CHAR["] pos=744 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
   5  208: CHAR[ ] pos=745 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
   6  216: CHAR[a] pos=746 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
   7  224: CHAR[d] pos=747 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
   8  232: CHAR[-] pos=748 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
   9  240: CHAR[A] pos=749 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  10  248: CHAR[d] pos=750 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  11  256: CHAR[v] pos=751 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  12  264: CHAR[i] pos=752 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  13  272: CHAR[c] pos=753 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  14  280: CHAR[e] pos=754 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  15  288: CHAR[-] pos=755 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  16  296: CHAR[d] pos=756 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  17  304: CHAR[e] pos=757 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  18  312: CHAR[l] pos=758 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  19  320: CHAR[e] pos=759 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  20  328: CHAR[t] pos=760 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  21  336: CHAR[e] pos=761 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  22  344: CHAR[-] pos=762 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  23  352: CHAR[f] pos=763 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  24  360: CHAR[i] pos=764 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  25  368: CHAR[l] pos=765 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  26  376: CHAR[e] pos=766 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  27  384: CHAR[ ] pos=767 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  28  392: CHAR[<] pos=768 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  29  400: CHAR[f] pos=769 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  30  408: CHAR[>] pos=770 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  31  416: CHAR[ ] pos=771 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  32  424: CHAR[ ] pos=772 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  33  432: CHAR[ ] pos=773 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  34  440: CHAR[ ] pos=774 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  35  448: CHAR[ ] pos=775 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  36  456: CHAR[ ] pos=776 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  37  464: CHAR["] pos=777 blev=0,btyp=L w=8 a+d=15+5 face=17 MB
  38  472: CHAR[ ] pos=0 blev=0,btyp=B w=8 a+d=15+5 MB

>> I can also drag the left window border a bit, so that (window-width)
>> still returns 34, but (window-pixel-width) is 291, then the lines in the
>> test buffer become not wrapped.
>
> The fact that pixel size changes, but the size in characters doesn't
> is expected, of course.

I wrote down specific numbers, for you to maybe try resizing the window 
to these dimensions. Like mentioned, I see the problem at 288px, and 
there's no problem at 291px, while the reported width in columns stays 
the same.

It's fairly hard to reach 288px though, because dragging with the mouse 
still moves the window border in jumps (even though not by columns).