Comment 13 for bug 762032

There's a remarkably similar bug in gnome shell: https://bugzilla.gnome.org/show_bug.cgi?id=597190
I've submitted a patch against mutter that fixes it, although it hasn't been accepted yet. I don't know how much is shared between mutter / compiz, but the thread and patch may be at least enlightening even if the patch can't be applied (assuming the reason for breakage is the same).