Lacking Rated 3 out of 5 stars
I dont know if its my combination of Firefox/Firebug/PixelPerfect, but here, when I refresh the page, the pixel perfect layer comp gets deselected, and I have to select it again to make it visible!
Because of that, if I want to use an overlay, Id rather make myself one as a transparent Div or a faded background image, so that I dont have to keep reactivating it.
Besides, as opposed to other firebug tabs, the Pixel Perfect tab never displays a scrollbar, despite its contents overflowing. Why?
My verdict... hasty implementation for something that could be useful, or at the very least be a cool extension to have.