Description of problem:

Lenovo T500 with displayport has a 1920x1200 monitor attached, I use the displayport in a similar way to a docking station in that I attach the monitor with a displayport to dvi cable, and then expect to be able to switch off the laptops internal display, only leaving the external monitor working.

Screen detection works fine, mirrored screen works fine, but disabling the internal display and activating the external display just leads to the screen going black until the timeout has been reached, whereupon it reverts to its previous setting.

I have tested this on both Ubuntu 11.10 alpha and betas fully updated as of today and Fedora 16 Alpha LiveCD downloaded today.

This works fine on previous versions, it's just the Gnome 3.x series that appear to be broken.

Happy to do whatever it takes to get this fixed.

Version-Release number of selected component (if applicable):
Version in Fedora 16 Alpha LiveCD.

How reproducible:
Every time.

Steps to Reproduce:
1. Connect external monitor via displayport on T500
2. Modify display settings to disable laptop display and just have external monitor working
3. Click apply
  
Actual results:
External and laptop displays go black and eventually time out, reverting to their previous settings.

Expected results:
The external display should light up with the full resolution and the laptop display should go dark.

Additional info:

I have raised an upstream bug: https://bugzilla.gnome.org/show_bug.cgi?id=659039
All logs can be found https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/828623