This really needs to be built-in Rated 5 out of 5 stars
Once I got it to display, it works perfectly and makes the 4.0 beta once again useable (which is good; I'm a huge fan of giving UI developers feedback!). I honestly don't think I could survive having to look at my url bar for what-url-is-this mouseovers, not to mention the ugly distracting mouseover animation and complete lack of status updates? Ugh.
Anyway, when I installed the addon, it appeared to do nothing, but after clicking Customize -> "restore default set", everything showed up and seems to be working perfectly. Thanks!