Firefox broke off backwards compatibility with massive amount of extensions - without them stock FF is quite shite and unusable. Not only that, some of the features of the old extensions are impossible to implement in the new extension engine.
Personally, I port my Chrome extension to a Firefox addons without much trouble, except for the stringent review process by a human developer which raised a lot my opinion of the firefox community.
The new extension engine shipped to the general public as part of Firefox 57 in November 2017.
While magicalbeans may be a bit hyperbolic in their criticism, as a web developer who uses all the major browsers, I am still annoyed every day by little things that are worse in Firefox since that time. It is a reasonable and valid criticism that many useful extensions were broken by the change and that a significant part of the functionality that was lost can't be reimplemented in the new system. The claims that the general reduction in functionality through loss of previous extensions would be a temporary problem and would be corrected as the new model evolved over subsequent versions have proven to be optimistic.
It is also fair to say that claims of extensions being better contained and more stable in the new model have been exaggerated. I see far more problems caused by the smaller number of extensions I now use than I ever saw before, and I have done consistently ever since the change, through three more major versions of Firefox itself and several updates to most of the extensions.
I appreciate the intent to make Firefox faster and more reliable and more secure. Surely no-one would argue that those aren't good things. But the fact is, a lot of stuff did get broken and hasn't been fixed, and for the class of users who valued Firefox for its customisability, it is a worse browser today than it was 9 months ago.
> some of the features of the old extensions are impossible to implement in the new extension engine
I am stuck on FF 53 (and reinstalling it whenever automatic updates sneak past me) since it still has the XUL API Pentadactyl uses to receive keyboard input[0]. The new WebExtension API don't expose the same level of functionality, so it can't be simply ported to them as is.
One approach to coping with quantum is to run 2 (or more)
Firefox profiles, one for the old, or ESR, or pre-quantum
executable; and the other for Quantum:
/usr/bin/firefox53 -P esr
/usr/bin/firefox -P quantum
and if you want access to the same saved bookmarks,
just use Firefox Sync to match them up.
It won't help with Pentadactyl, but folks with other use cases may find it useful.
