"spotlight" mask

hmm this probably has a simple answer, but i have a question about masking in flash MX

okay… so for instance in a normal mask, the mask (a circle for instance) reveals what is under the circle. now, what i want to do is create a mask that doesnt’ just show what is under the circle, but where everything else is darker or faded (lower alpha) but still visible… and the area under the circle is bright or 100% alpha (kind of like a spotlight effect).

if anyone can help (whether by AS or just timeline) it would be much appreciated. if you need more info or for me to be more clear, please tell me.

thanks :love:
-Jarviscares