It is a really nice thing which allows you to build very complex forms without your eventhandlers becoming cluttered with calls to other eventhandlers.
You can find some documentation in the blog, 2 entries in august 2005. (my blog doesnt support linking to items, so please find it yourself)
- download here
Like a drawing of M.C. Esscher, this XUL program can list and run its own XUL source...! (dutch)
- run here