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

[Eli Zaretskii]

> From: Andreas Schwab <schwab@suse.de>
> Cc: Bruno Félix Rezende Ribeiro <oitofelix@gnu.org>,
>   18912@debbugs.gnu.org
> Date: Mon, 03 Nov 2014 10:08:02 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Emacs never writes buffer contents where the mode line should be, so
> 
> Unless it needs to write a partial line just above the mode line.
> 
> > this problem could only happen if Emacs for some reason becomes
> > confused about the window dimensions.
> 
> Or the clipping rectangle is wrong for any reason.

It could be that, yes.  Although I generally need to enlarge the frame
by at least 3 pixels before Emacs enables another glyph row for such
clipped display.

Anyway, I hope dump-glyph-matrix will show if this is the case.