(This may be a duplicate but I haven't been able to find another bug on this particular issue yet--just the meta bug (#45522).) I'm putting this bug in xptoolkit but it's actually described as a mailnews bug (but I know I've been bitten by this in Composer and I'm sure it can happen in the browser as well). The following is reported by Jason Alcock on 11/15/2000 at http://www.macintouch.com/netscape6.html: Tooltip covers address window when typing in address.
Probably a dup of bug 53653, "Tooltips should go away when typing", currently resolved fixed with several comments saying it doesn't seem to really be fixed. ccing pinkerton, owner of 53653.
this was fixed post 6.0
adding nsmac2 keyword for completeness/queries