Default button placement Rated 5 out of 5 stars

Very useful and functional add-on. Just a quick note that might be of use to those not seeing the button: in Firefox 16.0.2 (and possibly 16.0.1) the button defaults to the navigation toolbar, so if you don't have one displayed, you will probably want to move it from there.

This review is for a previous version of the add-on (2.0.1-signed). 

I can see how this can confuse people

Hello there, thanks for noticing (and especially for reporting) this problem.
I will look into it, hopefully it will be possible to check toolbar visibility before placing the button up there.