Rated 5 out of 5 stars

This add-on is a must have for Fx 4! I very much like it!

In case you insert the button into the navigation bar it is lacking a padding of a couple of px to the right an left of the button, as it is the case for all other buttons like home, print, etc. I would be cool to have this too.

Another suggestion would be to allow the standard background colour for button on standard 4.0-theme and only have the little firefox as indicator. To cut it short, the option to have a light grey background as opposed to the orange on would be cool too.

I am using XP

This review is for a previous version of the add-on (1.3). 

Toolbar Appmenu Button
https://addons.mozilla.org/en-us/firefox/addon/toolbar-appmenu-button/