Hi, I made a few more tests in the gnome-fallback environment. Launching mutter and gnome-shell work fine !
Running gnome-shell --replace in a terminal gives a usable gnome shell application with compositing enabled. Now I wonder why gnome-shell is not called automatically when starting a nomal gnome 3 session. Can you give me more information on how gnome-shell is supposed to be launched ? Thank you. Regards, Jonathan Dray