Perfect FF3 Replacement Rated 5 out of 5 stars
As someone below pointed out, and as far as I can tell, this one works the same in FF3:
In an earlier review, someone said that FF3 already has this feature; you just double-click an empty space in the tab bar. This is NOT the same. As I look at my tab bar right now, I have seven open tabs already, and there is NO empty space to click on! This situation is where this button shines.