[ubuntu] Laptop with an external monitor at a different resolution

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http://ubuntuforums.org – At work I use a Dell Latitude E4300 with a resolution of 1280x800 and an external monitor with a resolution of 1280x1024. I'm runnin g Natty on it with Gnome 3. Everything is working OK, but the desktop seems to be 1024 pixels high on both screens, so it extends past the bottom of the laptop's screen, which makes using any sort of dock or just a bottom panel pretty annoying. Is there any way to limit the height of the desktop on the lower resolution screen without lowering the resolution on my external monitor? (Hardware)