Dual monitors on Ubuntu 8.04 bug July 6, 2008Posted by claudio in Uncategorized.
Tags: bug, dual monitors, gnome, Ubuntu
Nowadays, the GNOME screen resolution setting allows you to configure multiple screens pretty easy. It seems to work just fine. However, it’s a front-end to the X config an as such it has some problems. In my case, it allows me to clone my main monitor (is that useful to anyone?), but not to extend my desktop over both monitors.
The problem is related to the frontend not passing the errors from the underlying system (xrandr), so you don’t get any hints why it does not work. Maybe my home setup is kind of strange as I use two different resolutions (an LCD 1280×1024 connected though vga and the laptop 1024×768 screen as a second monitor), but still it shouldn’t be that uncommon. I enable the dual monitor setup when useful (gimp), but most of the time I find the different resoltion annoying. At work I use two 1680 x 1050 LCDS.
Anyway, the solution to enable a dual monitor is pretty simple.
In short, you need to edit the X config file and create a virtual desktop of the desired size. Just make the sum of the maximal size of both screen resolutions. In my case:
Monitors next to each other:
Width: 1280 and 1024 => 2304 (the desktop is extended in the width, so you need the sum)
Height: 1024 and 768 => 1024 (the desktop has the height of the biggest monitor)
One monitor below the other:
Width: 1280 and 1024 => 1280 (the desktop has the width of the biggest monitor)
Height: 1024 and 768 => 1792 (the desktop is extended in the height, so you need the sum)
Edit the X config:
sudo gedit /etc/X11/xorg.conf
Go to the Section “Screen”, then within to the SubSection “Display” (create it if not present) and add “Virtual <selected size>”:
Virtual 1280 1792
There is a catch. It’s more natural to create a virtual desktop with the screen logical next to each other, but I chose to stack them to keep the 3D hardware acceleration (compiz). Some video drivers (like my intel) disable hardware acceleration once your desktop is bigger than 2048×2048 pixels.