Somebody in the thread at some point said:
Also, maybe related but far less reproducible, very similar
behaviour
sometimes occurs when I switch workspace if I have a lot of windows
open. In that case the display is clearly wrong,
Does anyone know anything about this?
You don't mention which X graphics driver you are using in
/etc/X11/xorg.conf? If it isn't vesa, can you still make trouble with
your emacs resizing if you change it to vesa and restart X?
-Andy