Enable COMMAND-TAB in X11

I don't know why COMMAND-TAB doesn't work in X11. To get out of X11, I found COMMAND-H worked by hiding X11 but only if another program was running (I close the Finder so this can be a problem).

Like my CAPSLOCK tmux tip (http://coderwall.com/p/qa6fua), use Keyboard Maestro to create a trigger "This hotkey COMMAND-TAB is pressed" with action "Activate Application Switcher".

I configure the Maestro Application Switcher to always include Firefox and X11 so selecting one of those apps will start it if it's not running.