In what order do Firefox extensions get initialised?

Question

When a user has several Firefox extensions, what decides the order in which they get initialised? Specifically, in which order are XUL overlays applied? In most cases the order is not important, but it does affect things like the order in which items appear on the Tools menu, say, or in the status bar. Furthermore, being able to rely on the knowledge that extension A would be initialised before extension B could sometimes simplify coding.

I can't find this covered in any documentation, so any insight would be most welcome. Many thanks.

Answer 1

I believe it's in order of installation. At least it used to be so.