[drethemadrapper]

They (Moz. dev team) have now even gone wild by hiding the Addon SDK from developers. It's not on their servers but buried in github, covered by several versions of a new app./development tool. It took me a long time to locate it. It all appears that they don't want us to use it (perhaps because of the cfx they are deprecating for jpm). Yet, a developer needs it to upgrade or develop their (new) extensions ( xul->bootstrapped extension with/without the sdk lib.). On another note, extension development is now like a node app. dev. -- their directory structures now look like. It's funny yet interesting (standardizing addon dev.??).... This whole gospel about the SDK is a way of hiding the details/core of the FF browser from developers - ending the use of XUL/XPCOM, going HTML, e.t.c. Perhaps, Moz. needs to help make extension dev. easy for 'web designers'.

[asmicom]

I can confirm the increase in difficulty of writing FF extensions these days. There is no ONE go-to source for information.