bug#11070: 24.0.94; Large stippled images not displayed consistently

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: darthandrus@gmail.com,  rgm@gnu.org,  11070@debbugs.gnu.org
> Date: Sun, 29 Sep 2019 13:11:48 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Do those glitches disappear if, after scrolling, you type "M-x
> > redraw-display RET"?
> 
> Yes, M-x redraw-display fixes the glitches.

Then some redisplay optimization is at work here.  If your build was
configured with --enable-checking=glyphs, does the problem go away if
you set _all_ of the following variable non-nil?

  inhibit-try-cursor-movement
  inhibit-try-window-id
  inhibit-try-window-reusing

> > Also, could you (or someone else) try the same in some old version of
> > Emacs, say, 24.3?
> 
> The oldest Emacs I have here is 24.5, and the glitches are present
> there, too.

24.5 was after Stefan removed many redisplay triggers, AFAIR, so
that's too recent.  Does anyone have an older version on X and can
test that?  Emacs 23 should also be good.

Thanks.