[Gta04-owner] screen goes white on blank

[arne anka]

while charging the gta04 overnight i again was reminded of an issue that  
bothers me for a while now. not sure, if it came up and i missed it ...
here goes:

when the screen should blank due to inactivity, it does not become black  
(==turns off backlight), but instead white (==backlight still on).
i see this consistently with both debian on SD and the pre-flashed image  
in NAND.

is that known issue and what to do about it?