GrabMask is a union of core, XI1 and XI2 masks. If a XI2 grab is activated,
the value is a random pointer value, using it as mask has unpredictable
effects.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jasper St. Pierre <jstpierre@mecheye.net>
Reviewed-by: Keith Packard <keithp@keithp.com>