bug#18912: 24.4; mode-line corruption on graphical frames in dual-headed display

[Eli Zaretskii]

> Date: Mon, 03 Nov 2014 19:01:43 -0200
> From: Bruno Félix Rezende Ribeiro <oitofelix@gnu.org>
> CC: 18912@debbugs.gnu.org
> 
> >   M-: (pos-visible-in-window-p t nil t) RET
> > 
> > Please invoke this after "C-x d" in each case.
> 
> In the *good* configuration: (0 594 0 17 1 33)
> In the *bad* configuration: (0 594 0 17 1 33)

Again identical.  Looks like indeed it's some problem with your
graphics card, because Emacs gets the same information in both cases:
in both cases, only 1 pixel of the last line is visible.

I'll try to think about additional tests, but meanwhile I suggest that
you try lowering the level of the acceleration of your card, and see
if that helps.