Rated 5 out of 5 stars

It'd be great to be able to make custom buttons for thunderbird as well. are there any plans to port it there?

thanks!

This review is for a previous version of the add-on (0.0.4.3). 

albog, Custom Buttons works on Mozilla Thunderbird 2.0-3.0b3pre
it's also works on Sunbird/Calendar 1.0pre, Flock and KompoZer 0.8a2