I recently ran into a problem with GNOME 3 and my external monitor. GNOME 3 defaulted to displaying notifications and the activities overlay on what I consider to be my secondary monitor.
Investigating the graphical display configuration tools I was unable to find an option to change this. Luckily xrandr supports the setting of the primary display and GNOME 3 appears to take heed of it. To change primary display:
- Run xrandr to list available displays.
- Run xrandr –output
–primary to set the primary display.
In Fedora 15 the xrandr command is provided by the xorg-x11-server-utils package.
Update: Another viable solution has been posted in the comments. Unlike the one I have posted above it does not need to be done every time you log in. I am not sure how it performs in the event that you disconnect/reconnect the monitor or dock/undock the laptop frequently.