I maintain the AutoBar addon for World of Warcraft, but it needs more work than I have time to do right now. There are bugs in it's popup behaviour, I believe they broke sometime around the Wrath of the Lich King launch, so you need to be experienced with SecureHandlers.
There are 2 issues:
1) Popups often stay popped up even after mousing away. There is code to try to work around the bug, but it doesn't work anymore.
2) Optionally make popups only occur when a key modifier is down (shift key, for example).
The code is publicly available here:
[url removed, login to view]