Howto Lower brightness on Apple LCD Monitor? KUbuntu 10.4, KDE System Settings Display; jor XOrg

[giovanni_re]

Didn't get an answer on KUbuntu list, so hopefully someone here might
have a suggestion.

==
I've just installed an Apple Cinema Display (LCD) monitor. This is a 5
year old monitor.
Using KUbuntu 10.4

The apple website indicates this monitor has:
User controls (hardware and software):
  	Display power, system sleep, system wake, brightness and display tilt
http://support.apple.com/kb/SP79
http://support.apple.com/kb/SP77

Brightness is what I want to turn down.

Looking in the 
KDE System Settings > General > Computer Administration > Display > Size
& orientation > DVI-0

there is no adjustment for brightness.

Anyone know how to decrease brightness on this?

What sw manages the KDE system settings for Displays?  KDE? X?

Is there a way to turn down the brightness using some X config?

Is there a GUI for doing X configuration settings?

Thanks :)