Comment 13 for bug 470604

..update to my previous comment.

No amount of resetting defaults etc, seemed to work; I was able to work around this problem and put my system back to a 'usable' state by uninstalling compiz and reinstalling & enabling "Extra" effects from the appearance applet.

Note, another behaviour I noticed was that moving the mouse cursor out of the panel area and then directly onto a window, this would allow click -- oops, this is behaviour noted in post #4