Re: Redisplay issue

[Eli Zaretskii]

> Date: Sat, 28 Nov 2015 18:54:01 -0800
> From: Yuan MEI <address@hidden>
> Cc: emacs-devel <address@hidden>
> 
> > Can you see if the coordinates of the exposed region, as reported to
> > Emacs, correspond to what is in fact exposed?
> 
> Finally I captured a state that although an expose event was sent to
> Emacs (correctly), Emacs did not redraw.  In the attached screenshot,
> the left-side two windows are Emacs and speedbar frames.  The
> top-right terminal shows the output of xev monitoring the events of
> the main Emacs window.  This state was captured while shifting out of
> the virtual desktop containing Emacs then shifting in.  Emacs did a
> partial redraw only.

I don't understand how Emacs could redraw only partially, if it
received the correct coordinates of the exposed region.  I might be
able to understand how nothing could be redrawn, but partially?..
There's something I'm missing here.

Can you build your own Emacs?  The display engine can produce a trace
of what it does, but it isn't compiled by default.  If you can build
Emacs, then please configure with --enable-checking='yes,glyphs', then
type "M-x trace-redisplay RET" inside Emacs, and post here everything
it outputs to stderr starting with "expose_frame" when you succeed to
reproduce this again.

If you cannot build Emacs, then perhaps you could step with a debugger
inside expose_frame and its subroutines, and tell what's going one
there.

Thanks.