Dual Head with secondary actually secondary

[eteq]

I have a Mobility Radeon 9200 card running compiz-fusion beautifully under AIGLX in ubuntu feisty. But I've recently gotten ahold of a nice CRT, and I want to use it with the laptop LCD in a dual-head configuration. Problem is, the laptop LCD is already 1650 pixels wide, so MergedFB won't work with 3D acceleration unless the CRT is a ridiculously low resolution (e.g. 400 X 300, as the combined width has to be less than 2048 for 3D acceleration to work). So does anyone know how I can set this system up with either two totally separate compiz desktops (e.g. separate cube and everything), or alternatively, have the LCD be the full-up compiz desktop and have the CRT be simply a static desktop onto which I can just drag a few windows?

[adamk]

Unfortunately, it would be impossible to have two separate desktops as the radeon driver disables direct rendering if you configure X for more than one desktop. As for the other alternative you listed... If you can drag windows between screens, you have to be using mergedfb (or xinerama, which also disables 3D acceleration) and then both monitors are simply one screen, which means that one window manager has to control them both.

There is one possibility, though... What's the height of the laptop's LCD? If, for example, it's 1024, you could configure X so that the CRT is 1280x1024 and placed (virtually) *below* the LCD (or above). This would give you a maximum horizeontal resolution of 1650 (the width of the LCD), and a maximum vertical resolution of 2048 (the 1024 of the LCD + the 1024 of the CRT). If the height of the LCD is 1280, you could configure the CRT to be 768 pixels high (as 1280+768=2048).

Adam