Description of problem: In Fedora 15 alpha (all updates from today done except gdm which is buggy), when I change the luminosity, before seeing the correct picture of the luminosity being modified many macroblocks are displayed.


Steps to Reproduce:
1. Load gnome and wait a little until everything is loaded
2. In the laptop change the luminosity
3. See macroblocks then the luminosity changer indications
  
Actual results: no macroblocks.


Additional info:
I tried to see if it was due to a delay in the response but I waited I would say 1 minute after loading and on the first try it happens.
Then when loaded once it is harder to get it back. I am able to see it again, very briefly, with this:
* Change luminosity
* Change sound
* Change luminosity and sometimes the macroblocks are again here.

I will try to do a screenshot but it is very sudden...
The graphic card is in the smolt profile: http://www.smolts.org/client/show/pub_97a51b9b-9c31-4027-b192-acdfa7376036