What does fallback mode use for window manager?

[Tom Horsley]

Just tried f16 Beta TC2 on a spare test machine. It has
a GeForce GT 430 card in it, which cannot do 3D with the
nouveau driver, so gnome 3 switches to fallback mode.

In fallback mode whenever I bring up a gnome-terminal,
about 5 to 10 seconds later the window manager disappears.
All the window decorations go away and moving, raising,
lowering, etc is no longer possible.

However, I never get an ABRT report of any kind as near
as I can tell. It is more like it just decides to exit
rather than crashing.

Is metacity still the right component to use to report
this? Or does gnome 3 use something else for fallback?