window: wait until mapped before fullscreen
    
    On RHEL6, when starting virt-viewer --full-screen, metacity will
    remaximize & force-fullscreen when leaving fullscreen, which prevents
    user from accessing window titlebar, and end up with an incorrect
    fullscreen state.
    
    Thanks Owen Taylor for help debugging this:
    
    <owen> elmarco: So the interesting thing here is that the "legacy" isn't
           triggered off a configure request to a particular size, mutter seems to
           constrain the window back to fullscreen size on its own when it sees a
           change to WM_NORMAL_HINTS
    <owen> commit 4943d79d6844af3f7fc0a15ceadb69d95c4c5c61
    <owen> Author: Peter Bloomfield <PeterBloomfield@BellSouth.net>
    <owen> Date:   Wed Jan 20 10:59:07 2010 -0500
    <owen>     prevent window self-maximisation
    <owen> Is not in rhel6 metacity
    <owen> So probably that's the main difference
    <owen> can you just make your program not fullscreen initially but wait until
           it's mapped? (gets map-event on the toplevel)
    <elmarco> owen that seems to work
    <owen> I don't have a better solution to offer - sorry for the ugliness (code and
           initial mapping appearance)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=876445