Comment 4 for bug 145123

When compiz finds a fullscreen window, it calls "XCompositeUnredirectWindow()" on it. This has side effects that confuse gnome-screensavers lock dialog. It assume it has the keyboard grab already, when in fact it does not have it:

[gs_grab_move_keyboard] gs-grab-x11.c:324 (00:41:01): Window 2200024 is already grabbed, skipping
[gs_grab_move_mouse] gs-grab-x11.c:264 (00:41:01): Window 2200024 is already grabbed, skipping

the proposed fix changes this so that it will always (re)grab the keyboard.

This change needs to be tested as widely as possible before we publish it.