very odd screen goes dim bug in f12

[Linuxguy123]

On Sun, 2010-03-14 at 20:21 -0400, Mail Lists wrote:
> I just installed a fresh f12 - fully updated - lenovo T61p laptop -
> using nouveau.
> 
>  If i go to a virtual terminal - or if I set the run level to 3 (no
> graphics).
> 
>   After some period the screen goes dark - fine - however when I awaken
> the screen the backlight on the LCD display is almost off - starting up
> (or switching back to vt1) - the graphics are dimmed too.
> 
>   Rebooting does NOT restore the backlight - it remains dim.
> 
> 
>   If I now login - I have power applet on taskbar - suddenly (perhaps
> when power applet starts) suddenly screen goes bright again!!!
> 
>   Something about text vt's .. and dpms truly mucks up the backlight.
> 
>   Anyone else seen this weird/nasty[1] bug?
> 

Yes, I had that bug.  Try using the proprietary nvidia driver instead of
nouveau.   Also try tweaking the monitor brightness settings in your
various Power Profiles.