Rated 4 out of 5 stars

I was looking for exactly this feature!

My only comment would be: why not switch the functionality of both buttons? So that the top button closes the entire window and the smaller button below it closes the tab? I would like it even better in that way...

Anyway, good job!

This review is for a previous version of the add-on (1.1). 

Close Button should allow you to get the behavior you want.