Ratpoison is a lightweight window manager that is designed to require very little interaction with your mouse, hence the amusing name. That and the fact it also provides fullscreen windows with no decorations makes it ideally suited to a Myth FE system.
.xsession for ratpoison and mythtv
ratpoison & mythfrontend
External player commands may need some help to get mythfrontend fully focused on exit. eg.
xine <options> %s ; ratpoison -c focus