Ever since the first FUEL announcement, people have talked about a similar
extension API for Thunderbird.  Like FUEL, these interfaces would streamline
access to common areas of the application's interfaces using syntax more
familiar to javascript developers.  I've put together an initial proposal
for a set of interfaces that I think would be a reasonable start down that
path.  I came up with the name "STEEL" after spending about 5 minutes
staring at the back of the seat in front of me on a holiday flight, and
accordingly, the interfaces are available for comment at
http://wiki.mozilla.org/User:Jminta/Steel

Right now, however, this proposal is based entirely on my own experiences
and very limited knowledge of the mail-news codebase from my previous work
on the Lightning project.  Accordingly, I would love to collect other
thoughts on

   - What are notoriously tricky areas for extension integration in
   Thunderbird?
   - What are valuable, but perhaps under-utilized, areas of extension
   integration?
   - What was your experience like building a Thunderbird extension?

Comments are welcome in these newsgroups, or on the wiki-page.

-Joey