No it fades the same way based on the focus. It waits until something requests focus, and then plays the sequence with the fade. But it works nicely to switch it on once in a while.
..but I can't help but think that if I had ADD, I'd still want the entire screen to light up back to normal on some event (..or maybe just the status- bar, or the task- bar could light up? Perhaps, in the case of some alert - just the alert, or the new object, and the desktop could stay greyed out?) - and then it could fade back just to the working area after things disappear again... does that make sense..? I.e., you could list types of windows that would cause a light- up, and others that just would pass off silently, like ticking logs and so on (I mean, it sure would be comfortable that way, wouldn't it.