* clutter/clutter-stage.c:
        * clutter/clutter-stage.h:
        Add clutter_stage_set_xwindow_foreign() call
        * clutter/clutter-util.c:
        * clutter/clutter-util.h:
        Add some X error traps
        * examples/super-oh.c:
        Toy with us of new clutter_stage_set_xwindow_foreign() for
        optional screensaver functionality.