I have a laptop (Thinkpad X220t) freshly reinstalled with latest openSuSE (I 
did not yet have time to check under other distributions).

I installed Trinity over Gnome 3; If I boot and start Trinity (first user) I 
have nothing on the external screen (which is a beamer, 1024x768). Internal 
screen is at 1366*900.

If I start a second user (under Gnome) the internal screen resizes to 1024x768 
and I get an image on the beamer.

Thierry