Originally Posted by hdas
The biggest problem for me with twinview is that when one creates two desktops using twinview, it behaves like a single big desktop with double horizontal resolution. As a result, all apps open at the center, split between the displays, which makes it annoying.
That sounds like a configuration problem. Have you disabled Xinerama info? It's enabled by default and behavior of multiple outputs should be similar to Xrandr.
I agree that the missing Xrandr (1.2/1.3) support is annoying, though. None of the standard configuration utilities work correctly. I can't really understand it either, TwinView is doing everything Xrandr does and in very similar ways. Maybe I'm overlooking something, but it shouldn't be that hard to support another API like Xrandr.
Another showstopper of the open source drivers is missing support for GPGPU things, mostly OpenCL. Currently there's no development effort going on to fix that.