Where are the docs for creating Firefox addons?

Question

I'm trying to build a Firefox addon, but I simply cannot find the documentation for the internal (Firefox/Gecko) classes that addons may access. Or is standard DOM manipulation all that's possible?

Looking through some addons I see a lot of nonstandard Javascript objects created, so I'm sure there's more to extending Firefox than meets my eye.

   Components.classes["@mozilla.org/network/io-service;1"]

   Components.classes["@mozilla.org/preferences-service;1"]

Anyplace I can get a list of these classes and whats in them?

Answer 1

Here is the link for extensions: https://developer.mozilla.org/en/Extensions

and here is the link for plugins: https://developer.mozilla.org/en/Plugins

Edit: If you click on the Extensions link and read it, you will find many helpful things, such as How to Build an Extension. In that link you will see this information:

XUL files are part of "Chrome Packages" - bundles of user interface components which are loaded via chrome:// URIs. Rather than load the browser from disk using a file:// URI (since the location of Firefox on the system can change from platform to platform and system to system), Mozilla developers came up with a solution for creating URIs to XUL content that the installed application knows about.

Answer 2

I found it myself, at last. The full list of interfaces that Gecko exposes is available here, on Mozilla.org, this appears to be authoritative since the next link does not contain all these.

A list of interfaces built into Firefox (really?) is available here on the Mozilla Dev Center, and although most don't have any documentation at all, the important ones (blue links) have a page detailing the methods and properties within it.