I was thinking this should be position fixed in case you are scrolled half way down the page - you would not see the position absolute bar at the top, but it should be attached to the browser navigation right? The issue with position fixed is getting it to span the full width... any thoughts - maybe my UI sense is wrong here too?

[edit] Actually, doing a little testing on it now - position:fixed seems to just work. I like this solution a lot need to test it out... would be great to attach this to xhr progress events...