Dual head with xrandr

This was posted by İlkin Ulaş BALKANAY, on his blog. Thank you very much İlkin Ulaş, it did work for me too ;-)

I've got Ubuntu 7.10(gutsy) running pretty well on my DELL Latitude D505 laptop. I'll try to explain how I configured extended desktop with a NEC 19'' LCD monitor.
We will use xrandr utility to configure multiple screens. Before using xrandr you must check xorg.conf file ( /etc/X11/xorg.conf )

Section "Screen"
     Identifier      "Default Screen"
     Device          "Intel Corporation 82852/855GM Integrated Graphics Device"
     Monitor         "Generic Monitor"
     Defaultdepth    24
     SubSection "Display"
             Depth   24
             Virtual 2304    1792
             Modes           "1280x1024@75"   "1024x768@60"
     EndSubSection
EndSection

The Virtual keyword is important. Sum of resolution widths and sum of resolution heights of two monitors are written in Virtual.

For example : 1280 + 1024 = 2304 and 1024 + 768 = 1792

You must restart X server after updating xorg.conf file. ctrl-alt-backspace is the shortcut to restart X. After successfully restarting X server, run the following commands:

xrandr --output VGA  --mode 1280x1024
xrandr --output LVDS --mode 1024x768
xrandr --output VGA --right-of LVDS

First command sets VGA (19'' LCD monitor) resolution to 1280x1024. Second command sets laptop monitor resolution to 1024x768. The last command places the extended monitor (VGA) right of laptop monitor. That's it. At least it works for me.