Using 64-bit Ubuntu 11.10 and integrated (Intel) graphics, I can run the 1600x900 laptop display plus a 1600x1200 external monitor connected to the VGA adapter. But my external monitor is 1920x1200 so I have black stripes on each side.
I believe the resolution is limited like this as the maximum resolution available from the Intel GPU is 2560x1600 = 4,096,000 pixels and I'm asking for a 3520x1200 = 4,224,000 display (with 1200x300 lost above the laptop screen). At 3200x1200 = 3,840,000 pixels, the Intel GPU seems happy.
Under Windows, the same limit exists when using the VGA adapter, but if I turn Optimus on then I can connect the external monitor to the DisplayPort and get its full resolution and an extended desktop.
I've seen that Bumblebee can run apps on the DisplayPort using the 'optirun' command. My question is: can Bumblebee run the DisplayPort in concert with the Intel card running the laptop screen creating a large virtual desktop (as on Windows)?
If so, are there any pointers to how to do this? I tried once, failed, and dropped back to Integrated Graphics (and black stripes) as I could find no reports of this configuration working.