great! Rated 5 out of 5 stars
very clean UI.
there was a guy complaining that it may be too big. well, in that case, just customize firefox to use small buttons (dah).. i think that will suite your needs.
so, to sum up, great work! :)
PS: it would be nice if you could make some custom buttons for the other windows too (i.e. addons/options...)