I recently upgraded from Lucid to Maverick, and noticed a regression. I have a keyboard shortcut Mod4+p (aka Super/Windows key) bound to run the command "rhythmbox-client --play-pause". I've had this shortcut since Karmic, it always worked fine.
After upgrading to Maverick, the shortcut still works to play/pause Rhythmbox, but the entire screen flashes when I press it. That is, the screen appears to go entirely black and then redraw very quickly (probably less than 10ms). I'm running metacity, not compiz, but I suspect it's not a metacity bug. I have a local build of metacity in my home dir, and the bug occurs with that build as well (and this executable worked fine pre-upgrade).
Digging through the keyboard shortcuts and even searching in gconf-editor, I can't find any other shortcuts bound to <Super>p that could be interfering. If I reassign to Mod4+r, the shortcut works and no flickering happens. It's something special about Mod4+p.
uname -a: Linux crono 2.6.35-22-generic #35-Ubuntu SMP Sat Oct 16 20:45:36 UTC 2010 x86_64 GNU/Linux
version signature: Ubuntu 2.6.35-22.35-generic 2.6.35.4
If it matters, the hardware is a Dell Precision M6400 with an nVidia Quadro FX 2700M video card. Any input would be appreciated.
Just tested in compiz instead of metacity - the flicker is faster, but still present. (Visual Effects set to "Extra", before with Metacity they were set to "None".)