I have got 12.04 on my Desktop machine. I have also two dell monitors 24" and 22". My graphics card is "04:00.0 VGA compatible controller: ATI Technologies Inc R680 [Radeon HD 3870 x2]". I have searched and tried proposed solutions here and none work. I also tried xrandr but it behaves strangely. With xrandr, I cannot get the resolution right and the Fluxbox bottom bar is in the extended monitor (22"). Is there an easy way to get the extended desktop working correctly with Radeon HD 3870?
To fix it:
monitor 1 (24",1920x1080): monitor 2 (22",1680x1050):
info about the monitors:
Command that actually sets the monitor: