Rated 5 out of 5 stars

Rather than recommending Hide Menubar, I will suggest to use Compact Menu 2.
https://addons.mozilla.org/en-US/firefox/addon/4550

I've used part of your skin to make an example custom icon
http://img189.imageshack.us/img189/9592/menuku.png

Finally it will look like this;
http://img69.imageshack.us/img69/4690/compactmenu.png


Nice work!! Great skin, I love it!

This review is for a previous version of the add-on (0.5.4).