Comment 134 for bug 568611

On my GMA4500 setting brightness to minimum turns off backlight completely, but with external lighting something can still be seen on a screen (because the image is still there, even though there is no backlight). It looks similar to what the reflective cell phone's screen looks like when it goes dark - you can still see symbols on the screen, but you wouldn't be able to see them if you were in a dark environment.

So I believe power manager should not allow setting brightness to absolute minimum.