Great little extension for TB. I need to use subscript/superscript formatting all the time and it's a godsend to finally get that on the compose formatting bar. Surprised this hasn't been submitted to AMO as an official release...I would've been using it years ago if I knew it existed.

As an FYI I can confirm that current v1.2 does indeed work on Thunderbird 6 by bumping the maxversion number. Also tested and working on TB 9.0a1, so bumping the maxversion to 9.* should keep it fully fresh for the next few TB releases.