One of the goals for Thunderbird 3 is to be a much better platform for which to develop add-ons.
We’re planning and doing some in-product and in-codebase work to that end, including documenting APIs (shocking, I know), bundling STEEL, which should make it easy to do 80% of what add-on authors want to do without resorting to XPCOM voodoo, and in general refactoring to make more capabilities pluggable.
But I’d like to find out what else we can do. Are there enough ways for add-on developers to get help? Do you know where to ask for various kinds of questions? Add a comment if you have ideas, please.
I’ve been emailing with David Boswell and Eric Jung from mozdev, trying to figure out if there’s something the two organizations can do together, as we have some natural overlap in this area.