I have three monitors, an HD3200 (igp) and an HD4670. I have all three monitors working, but the two monitors on the HD4670 are one display (:0.0) and the third monitor is a second display (:0.1)... so I have two separate desktops and I can't drag windows between them. (or open firefox on both of them... and a number of other annoyances.)

I thought that this was the best that was possible with current drivers, but I just saw this quote from bridgman in another thread:

Your best bet for multi-GPU support with 6xx-and-up GPUs today would be fglrx, since it already includes all the functionality for splitting drawing commands across multiple GPUs and screens.
Maybe in my hopeful expectation I'm reading too much into that, but "splitting drawing commands across multiple GPUs" sounds like it might mean "drawing half of a window on one GPU and the other half on another GPU".

Is it possible to get a third monitor to work like "normal" with AMD cards on linux?