[winswitch] Using Xpra on multi-GPU laptops

[Eric Appleman]

Hi, I've been fiddling around with Xpra as a replacement to the 
Bumblebee Project's[1] VirtualGL backend. Bumblebee permits access to 
the Nvidia GPU on Optimus laptops. By using the X server it creates, we 
can start applications on the invisible Nvidia screen.

I want Xpra to replace VirtualGL as the transport method, but I need the 
screen to display at a normal framerate.

I've included a demonstration that compares rendering through Xpra and 
without it. Feel free to drop by #bumblebee-dev on Freenode if you have 
ideas or questions.

Thanks.

- Eric

[1] https://github.com/Bumblebee-Project/Bumblebee

Example:
http://www.youtube.com/watch?v=IN8heIMqTa8

1. Start Bumblebee X server on :8
optirun glxinfo

2.Start Xpra server
xpra start :8

3. Attach :8 to :0, the Intel screen
xpra attach :8

4. Start applications on Nvidia screen
DISPLAY=:8 glxgears

5. Repeat step 4 as necessary