https://bugs.freedesktop.org/show_bug.cgi?id=91202
--- Comment #6 from Mathias Tillman master.homer@gmail.com --- I know this may not be a very useful comment, but I can confirm that this bug also happens on 4.2-rc7, and that changing the display resolution via xrandr makes it come back. I set up a script that's run when X11 is started that changes the resolution (and then back again) as a temporary workaround.