I developed this technique to darken my MegaPixel display completely when I
log out to prevent further burn-in of the login dialogue box.  This technique
has been tested under NeXTStep 1.0 and 2.0.

1) I created a small program to manipulate screen brightness, called VidLev.

2) I used the suggestion from Art Isbell <isbell@ucscf.UCSC.EDU> about
   loginwindow's LoginHook and LogoutHook defaults, defined LoginHook and
   LogoutHook shell scripts, and declared them root's loginwindow defaults.
   The LogoutHook script uses VidLev to darken the screen.  The screen stays
   dark until the "brightness up" control key is pressed.  (Moving the mouse
   or typing to the login dialogue box will not automatically re-brighten the
   screen until 30 minutes after the last logoff -- pressing "brightness up"
   always works.)

3) VidLev stays in the background and re-darkens the screen every 10 minutes,
   because some process -- maybe loginwindow -- "dims" the screen to a
   brighter level after 30 minutes.  I tried modifying AutoDimTime for root's
   NeXT1 and loginwindow -- that had no effect.

4) At login time the LoginHook shell script sends a SIGHUP to the background
   VidLev, causing it to restore screen intensity to values remembered from
   logout time.

Vic Abell <abe@mace.cc.purdue.edu>
