Rated 1 out of 5 stars

Nice button. That's about it. Nice button.

Doesn't do anything. No zoom with this add-on.

Đánh giá này là cho một phiên bản trước của tiện ích (0.0.6). 

Will you please tell me what operating system that you're using and what version of Thunderbird?

This add-on has been available on this site since February 28, 2012 and this is the first time that I've heard that it doesn't work. I use it myself.
It accesses and triggers Thunderbird's default zoom feature and that's about all there is to it.