I'm using the newest 12" PB and when I turn the screen brightness all the way down to zero using those function keys (F1 & F2) then I'm still able to see the desktop, although it's very, very dim. So why is it so? I mean is there any reason why the screen doesn't switch itself completely off or go to sleep? Also an interesting fact: when I switch off all the lights in my room and make it completely blind, I cannot see anything on the screen when the brightness is turned down. I see the desktop only when the room is considerably bright. That made me think that the screen might use brightness from outside of the machine to show items on the screen instead of using the computer's own energy to light the screen. Or it doesn't make sense at all?