Rated 3 out of 5 stars

"Since version 1.1, you can add a button to close the whole window."
OK, I give up. How do you do that? I can't find anyting like a setting.

This review is for a previous version of the add-on (1.4.1-signed). 

Thank you for your feedback.
You can use the "Customize" Firefox command (by right clicking on a toolbar) to add the button where you want.
Thanks to your comment, I've added a note to the extension description.