Screen too dim on login after reboot

[Joe Riel]

Whenever I reboot my laptop, then log into xfce,
the screen is too dim.  To restore it to the
preferred brightness, I logout, log into gnome,
then out and back into xfce.  Logging into gnome
increases the brightness; fortunately it remains
when switching from gnome to xfce.

Any clue as to what setting I can change in xfce
to avoid having to go through gnome?

Thanks

-- 
Joe Riel