Code review comment for lp://qastaging/~banw/compiz/compiz.a11y-shotcuts

Checking things again, it seems XI2 normal events are not affected by grabs, or
at least the ones I have tried: inside gtk3 menus and in screen saver

I can confirm that listening to XI2 normal events prevents core events from
being delivered, but that's only for compiz for the windows not created by
compiz, so it's not a problem for other applications. For compiz itself, I don't
think it is a problem that core events are not delivered any more: once XI2 is
enabled, I don't see a reason for doing anything with the core events (on the
contrary, that would lead to duplicates), so their processing could just be
disabled in that case. Was it only needed so as to detect whether grabbing was
enabled or not? That can be detected more easily with FocusIn/Out with mode
NotifyGrab/Ungrab.

I'll try to rework the solution with XI2 normal events only.