[gpm] luminosity issue

["Pascal Terjan" <pterjan gmail com>]

Hello,
when the screensaver starts luminosity is lowered, but when I unlock
it, it is not restored and I have to increase the luminosity by hand.
If I uncheck "Dim the display when the computer is idle" this does not occur.

I'm using 2.17.3 and did not build CVS recently, so this might be
already fixed :)