I have finally got Version 1.0 of Toolbar Buttons out. It finally brings the extension up to speed with supporting the latest releases of Firefox and Thunderbird.
The extension also got a visual refresh, it is now using my own icon set. Though some of the icons still need work (particular those of the larger icon size) it has been mostly fixed up.
Also quite importantly, and what has taken the most time with this release, is the extension had large internal changes. It is now much easier to add new stuff, and keep track of what buttons are their. Already encouraging some people to contribute new buttons to the extension. It also opens the possibility of doing some exciting stuff with the Custom Toolbar Button maker, at least as soon as I get that updated.