How can I switch window managers in Gnome 3?

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http://unix.stackexchange.com – I normally enjoy using Gnome 3 and gnome-shell in Fedora 16. However, I would like to temporarily run a non-compositing window manager such as metacity so that some wine games can have full control of the display. I have metacity installed. When I run metacity --replace, instead of switching window managers I get a gnome-shell failure display that forces me to logout. I also cannot find a way to choose a different session from the login prompt. There are no buttons, options, arrows or anything to choose. Just username and password. I'm about to resort to desperate measures involving systemd (HowTos)