new addons: xul, bootstrapped, webextensions, what to use

Mark Rousell mark.rousell at
Sun Sep 2 22:46:43 UTC 2018

On 02/09/2018 23:27, Philipp Kewisch wrote:
> Thunderbird 60 will persist until Thunderbird 60.9.0, which is set to
> release some time around October 2019 and coincides with the Thunderbird
> 68.1.0 release.
> Using XUL add-ons is not recommended. bootstrapped add-ons will exist
> until about Thunderbird 65. What you should look into is WebExtension
> Experiments, and devising Thunderbird-specific APIs around that.
> Unfortunately Thunderbird 60 is missing some of the more important basic
> WebExtension features, but I hope to backport this in an upcoming minor
> release. They work fairly well in nightly though.
> You can read more about WebExtension Experiments in Thunderbird here:
> If you would like an intermediate path, you could aim for a bootstrapped
> add-on. Note however you will need to rewrite to a WebExtension at some
> point before Thunderbird 68. Upgrading from a bootstrapped add-on to a
> WebExtension could be less effort than doing so from a XUL add-on, but
> my recommendation would still be to write it as a WebExtension Experiment.
> I'm sure this brings up a lot of questions I'd love to answer, and more
> importantly document so that others can benefit. It would be great if
> you could help us identify where we need to improve our documentation.

May I suggest that it might be very helpful if you or Jörg update with information.
It adds to and expands on the information already in the wiki article.

Can I just confirm what major version numbers of TB are intended (as
things stand) to be released and what their addons support is intended
to be?

60    :    Already released.
61    :    Will not be released.
62    :    Will not be released.
63    :    To be released. Currently last release to support XUL addons?
64    :    ?
65    :    To be released. Currently last release to support
bootstrapped non-webextension addons?
66    :    ?
67    :    ?
68    :    To be released. All addons from now on to be webextension?

I know all this is subject to change so I'm only trying to get a clearer
idea of how things stand today.

And that classic question: Just how flexible will webextension (or
should I call them mailextension) addons be in terms of UI flexibility
compared to current addons?

Mark Rousell

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