Personally, I'd like a way to turn 'em off.

What I've seen.

Firefox at home, most recent update, holds a one-line box for 5 seconds or so. If I move the mouse or touch a key, the box disappears.

IE version 7 I think at the local community college, shows a multiple-line box for an unremembered length of time.

Fred

__________________
"For shame, gentlemen, pack your evidence a little better against another time."
-- John Dryden, "The Vindication of The Duke of Guise" 1684