I am running Ubuntu 12.04 (beta) with a triple head setup and GNOME 3 desktop (ie "GNOME" selected not "Ubuntu" at login screen). It seems that it handles multiple monitors by blessing one monitor to receive the Activities bar, Clock, Login Menu, etc. Let's call this the "primary" monitor. How do I change it (permanently) ?
Update: Ok so:
$ xrandr --output DFP4 --primary
Does the trick temporarily. How do I make it permanent? I'm using latest fglrx ATI Catalyst driver