Rated 4 out of 5 stars
Very nice idea and good customization options. Very nice that you can keep some icons unhidden by increasing the minimum size. Worked fine in Firefox 16 for me.
It isn't useful to me, though, unless I can maximize the addon bar to it's full width when clicking the arrow. I moved my url box down to the Addon bar so I can hide my address bar (since FFx won't let you move certain status icons.) With this extension my url is completely hidden and there's no way to show it. In addition, I have no way to Search from the url box (using Omnibar.) I will look for an autohide extension instead. But Thank you!