Are most of the existing add-ons being sacrificed due to adding support for WebExtension?

Tony Mechelynck antoine.mechelynck at
Wed Nov 22 06:05:41 UTC 2017

On Wed, Nov 22, 2017 at 4:08 AM, Eric Moore <emoore at> wrote:
> "In general, there have been many interface/IDL changes over the
> mozilla57/58/59 period and some changes to JS syntax that most add-ons will
> require some sort of update to their code. That will distinguish the
> "maintained" add-ons from the "unmaintained" add-ons some/most of which will
> stop working.
> ....
> Jörg."
> Who made the decision to essentially kill off legacy add-ons and when was it
> made?
> Who was aware of that decision?
> Why wasn't this treated as a strategic decision that needed
> feedback/discussion like was done with getting a new home?
> A lot of what makes Thunderbird so popular is its large collection of user
> developed add-ons. My impression is that many users have given up due to
> poor doc., too frequent changes to interfaces, and uncertainty about the
> direction of add-ons. Look at Paolo "Kaosmos" for example. A cookbook on how
> to convert a legacy add-on and migrate to a new add-ons web site isn't going
> to change that.
> What is the plan to deal with the bad publicity when web sites like
> hear of this?

Most of the answers to the above depend on the fact that it was a
Toolkit decision, not a Thunderbird decision. It was announced,
especially in Firefox media, that Firefox would stop supporting legacy
extensions from release, er, IIRC it was 57, onwards. Fx57 is now
Beta, the bleeding-edge development version is now 59.0a1, and during
the two latest "release train cycles" the Firefox, Toolkit, etc.
developers have been removing "dead code" all around the town. "Dead
code" in their own eyes of course, meaning code no more used in
Firefox. Whether Thunderbird or SeaMonkey still uses the code is the
least of their concerns.

Best regards,

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