Well, imho, there is a perfectly good reason for this. XUL was never a specification. It was never a spec, nor a standard.

It has been around for quite a long time, but no-one other than its -initial- lead developers even cared to draft anything that resembled an interoperable specification. The primary idea would be to specify what should be, develop what can be, modify the spec for practicality and then publish something like “XUL 1.0″ when its all said and done.

Then if there is a need to iterate the design document(s) you can do so. As it stands now, XUL is neither a standard, nor in-and-of-itself a stable platform to develop ANY application on, there isn’t even a set of stuff said “not to change in functionality”, not even or are frozen.

Though many of us in the mozilla world know what to expect with a wide variety of XUL, including the fact that and probably won’t fundamentally change in the foreseeable future; but this is neither documented, nor specified anywhere (that I have seen).

I for one would have loved to see XUL take off, but even in my early years here, I was looking for the spec and told “we’re not working on it anymore, you want the spec, read the code” which is suboptimal and w/ regard to this post screams of “we want you to use XUL not your own XML based language, `how does it work` well, quite simple actually, either use Gecko or read our code and create your own program to use it” :/