Rated 4 out of 5 stars

Nice work, Joe! I've filed a bug 24926 to add SeaMonkey support and better detect the application in which this is installed, but some minor editing got it working for my test setup, and it looks really nice.

The code is elegant and the rendering is clean and legible. Very, very well done.

This review is for a previous version of the add-on (1.0.0.2).