Wednesday, June 11, 2008

Howto setup dual screen for Compiz in Ubuntu Hardy

If you need to give presentations with your laptop and you are running Ubuntu Hardy, you might find that the gnome-display-properties (System>Preferences>Screen Resolution) do not work out of the box. So it is impossible to connect a beamer unless you clone. The same is true for a dual screen setup with Compiz.

There is however a very easy trick to solve this. I have tested it with an Asus Eee PC 701 4G and with my Ati Radeon X600 desktop system. I am now enjoying running dual screen with all the 3d desktops enabled.

The problem is that the default screen size configuration is too small, which does not allow you to place too screens next to each other. On the other hand Compiz can not handle texture sizes bigger than 2048x2048, which means for example two monitors of 1024x768. If you want to use bigger resolution, it is still possible, but you will need to turn off compiz and will loose the 3d effects.

So to solve it, fire up a terminal:
$ sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
$ sudo gedit /etc/X11/xorg.conf

Then find the "Screen" section and change it like this:
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
SubSection "Display"
Virtual 2048 2048

To undo, you can just type:
$ sudo cp /etc/X11/xorg.conf.backup /etc/X11/xorg.conf

After doing this, you will be able to use gnome-display-properties with ease and run dual screen setups like this:

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