I managed to fix problems with keys being stolen on 10.10 by disabling a bunch of bindings in compiz (see Which program is stealing my keyboard events?), but I just upgraded to 12.04 and encountered a similar problem with Meta-p (or Super-p or Mod4-p or whatever alias is currently in vogue for this combination). I'm not using Unity, and I've disabled every key binding that I can find in both compiz and the keyboard configuration tool available from system settings, but Meta-p will still not come through and it is driving me crazy. Here is the output from xev:
KeyPress event, serial 36, synthetic NO, window 0x4000001, root 0x15a, subw 0x0, time 3301442, (44,140), root:(1757,192), state 0x0, keycode 133 (keysym 0xffe7, Meta_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False FocusOut event, serial 36, synthetic NO, window 0x4000001, mode NotifyGrab, detail NotifyAncestor FocusOut event, serial 36, synthetic NO, window 0x4000001, mode NotifyUngrab, detail NotifyPointer FocusIn event, serial 36, synthetic NO, window 0x4000001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 36, synthetic NO, window 0x0, keys: 90 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
My interpretation of this is that window 0x0 (is this the window manager?) is grabbing this key combination but I have no idea why. I've spent a lot of time trying to get this setup configured and would hate to have to switch window managers at this point, but stealing this key is just not acceptable, period. Does anybody have any idea what is going on here?