WebExtensions API and Deprecation of XUL, XPCOM and XBL

The most recent Mozilla Add-ons Blog announced that Firefox will introduce the WebExtensions API and that XUL, XPCOM and XBL would be deprecated. There are a couple of points that I would like to clear up:

  1. Will the WebExtensions API be added to both SeaMonkey and Thunderbird?

  2. Will XUL, XPCOM and XBL be deprecated in SeaMonkey and Thunderbird?

I have an extension being reviewed that works with all 3 of them and would like to know if I’m going to have to create a separate version for Firefox and another for SeaMonkey and Thunderbird.

Can someone please enlighten me. Thank you.

That are questions than only the maintainers of Thunderbird and Seamonkey can answer.

Thank you for your response. I am hoping that the Thunderbird and SeaMonkey maintainers read this forum so they can clarify this issue. If there is another forum that I should subscribe to specifically for Thunderbird and/or SeaMonkey then I’d appreciate a link to it. Thank you.

It’s way too early to say how Thunderbird will respond to these changes in addon technologies. Generally our issues are very different than Firefox. For example, compatibility with Chrome extensions is of no value to us. Also the prevailing view so far is that we will not require addon signing. If I had to guess, I would say that we will delay as long as possible deprecating XUL and XPCOM.

But we share 90% of our code with Firefox. As Firefox make changes that deprecate XUL and XPCOM, eventually we’ll have to either adapt, or stop keeping current with Gecko versions. It would be a difficult decision to stop using current Gecko code.

R Kent James
Chair, Thunderbird Project


Thank you, Kent, for your reply.

I thought that Thunderbird would be staying with XUL and XPCOM for the time being but I appreciate your confirmation of that. I hope that SeaMonkey will also stay with XUL and XPCOM but haven’t heard anything yet.