Rated 5 out of 5 stars
Brlliantly simple addon, but really rather useful. Installs and runs fine in Mac OS X on FX 3.0
Couple of possible suggestions to improve:
1) Once you start to get over 14 tabs, each tab size is so small that the "1# " text actually takes up a little bit too much room. Consider removing the # symbol if tabs>14, or leave out completely.
2) Instead of above, maybe place the "1# " text instead of the close tabs image, which is only useful when mousing over. Bit if css trickery to have number normally, x button on hover?
Aside from that, great work!