Likely timing of future Thunderbird Gecko builds

Magnus Melin mkmelin+mozilla at
Tue Apr 18 19:57:59 UTC 2017

For what it's worth, I think your estimate is very pessimistic. There 
might be some more breakage around 57 when extension-only code can be 
removed, but after that with some luck we're back to the usual state.

I agree with Ben discussing a fork is not a very useful, because that's 
basically when you close shop. Why anyone would put effort into 
improvements into that forked product? It would be just lipstick on a 
pig, a pig on the way to the slaughter house.


On 4/18/17 8:22 AM, R Kent James wrote:
> TL;DR: Our branch of Gecko-esr59 may be the last version of 
> mozilla-central that we support for Thunderbird.
> ------
> In my post from September 17, 2015 "Future Planning: Thunderbird as a 
> Web App" I proposed a likely future schedule. I said:
> "Thunderbird 59:  Last and traditional XUL/C++ release. By this date, 
> a reasonable possibility is that the Mozilla platform will no longer 
> be usable for non-browser XUL-based development. This version of 
> Thunderbird, in that case, would need to ship on a fork of Mozilla 
> from the point where XUL-based development becomes untenable. This 
> will also be our last major XUL-based release, and we will not attempt 
> to keep current with the new non-XUL Mozilla platform."
> Though 19 months have passed since that post, I still stand by that 
> timing, and I think we need to seriously start planning our likely 
> relationship to Gecko releases. Mozilla is talking about major changes 
> beginning with Gecko 57, so we will probably need to branch Gecko at 
> that point. We'll try to keep the branch as close to Gecko-esr59 as 
> possible, so that while Gecko-esr59 is active we will be able to merge 
> security changes. After EOL of Gecko-esr59 in late 2018, we will be on 
> our own, responsible for continuing security updates to our mozilla 
> branch.
> That means that after Thunderbird 59, we will cease trying to maintain 
> Thunderbird builds based on Gecko 60 and later, but will instead 
> continue all further development of existing Thunderbird (which should 
> be regressions and security patches only) using Gecko-esr59. After EOL 
> of Gecko-esr59, that will require increasing effort to maintain 
> security patches, such that this path is probably only viable for at 
> most a year after EOL of Gecko-esr59.
> That also means that during the mozilla-maintained lifetime of 
> Gecko-esr59, we will need to devote all available effort and resources 
> in a race against time to have a viable Thunderbird++ before the costs 
> and risks of maintaining our fork of Gecko-esr59 becomes untenable.
> What might change this? If the mozilla breakages at Gecko 57 are less 
> than we fear, it might be possible to to continuing maintaining a 
> Thunderbird build on Gecko for 60+. But we should make a hard decision 
> at that point, and not just assume that we will continue the 
> substantial effort to keep Thunderbird buildable on mozilla-central.
> Per current schedule 
> for merge of Firefox 60 to central is 2018-01-15, so we will need to 
> decide before the end of the year whether to cease attempting to build 
> Thunderbird on future Gecko versions.
> :rkent
> _______________________________________________
> tb-planning mailing list
> tb-planning at

More information about the tb-planning mailing list