Recently I wanted to test a keyboard shortcut, which is supposed to kill X server (hence very useful when you have a crash). That shortcut is not dependent on any particular window manager (like lxde, unity, kwin etc). So, it must work, even when you have unresponsive (to keybings) window manager (as opposed to Alt+Ctrl+Backspace which kills the session, and bring you a login screen).

That's why I interested to make my window manager(unity) unresponsive. Is past, it was very easy. Opening a terminal, typing unity --replace and then force close the terminal, was the simplest procedure. But unfortunately, This is not true in Ubuntu 12.04, (they make it very robust) Because whenever I kill the terminal, Unity automagically restart itself.

I also tried compiz --replace but wasn't successful.

My question is: How can I make Unity unresponsive to any keyboard shortcuts (of it's keybindings) while I am in Unity session, so that I can test the global shortcut.