Excellent add-on Rated 5 out of 5 stars
I downloaded this add-on from the developer's website over a year and a half ago. I've been using it on multiple machines. It's as solid as any add-on I use.
It was clear to me for a long time that the tab-across-the-top layout is very cumbersome. Especially since I tend to keep a lot of tabs open. The tree style make much more efficient use of screen space. And, it's very convenient to start a Google or Amazon search, open up a bunch of tabs, and then be able to close them all with one right-click menu choice.