Thunderbird and Addons

Axel Grude axel.grude at
Wed Aug 26 15:48:28 UTC 2015

A couple of questions from my perspective as author of heavily 
"chrome-layer"-dependent Tb extensions:

Could we design a survey for Thunderbird Addons authors to ask them what kind of 
objects they use?

I usually go through Components.interfaces and Components.classes to get access, if 
their usage were deprecated I would advocate creating a wrapper API. I am not quite 
sure what "counts as" XPCOM but I go by the classification on msdn (which includes all 
of the .nsI Interfaces and .ns* constructs)

Also does moving away from XPCOM also include a restriction of accessing global variables?

Finally for me the reliance on XUL to modify the "main" user interface (outside of 
content tabs) is a vitally important requirement, I wonder how Firefox deals with 
this? Moving its complete UI into Content Tabs, like seen in Chrome feels like a lazy 
hack. Certain things like modeless floating windows are impossible to achieve (or 
maybe not anymore?). Are there some specialists on the list who are up to date with 
the current API in Firefox? Can it be reused in Thunderbird?


*Axel Grude <mailto:axel.grude at>*
Software Developer
Thunderbird Add-ons Developer (QuickFolders, quickFilters, QuickPasswords, Zombie 
Keys, SmartTemplate4)
AMO Editor Get Thunderbird!

> *Subject:* Re: Thunderbird and Addons
> *To:* R Kent James, Tb-planning
> *From: *Philipp Kewisch
> *Sent: *Monday, 24/08/2015 20:48:43 20:48 GMT ST +0100 [Week 34]
> While in the short run I'd agree to all three points you mention, I think we need to 
> plan on how we will interact with the new addon plans of Mozilla. If we go with this 
> statement now and only make changes when core Mozilla code no longer supports it, it 
> will be way too late to transition Thunderbird addons then and we will have an even 
> bigger problem.
> I do think that we should try to make the most out of what they are doing with Web 
> Extensions and System Extensions. If this is what it is going to be, then we'll need 
> to provide a set of APIs that Thunderbird addons can use, based on what our addons 
> are currently doing. I've added two ideas to the uservoice page [1] [2] (plus my 
> comment on [3]) that would benefit Thunderbird, if you have a moment please vote :)
> It is a bit to early to make concrete suggestions on what a such API will look like 
> since I am still unsure how they plan to replace the xul overlaying which we make 
> more extensive use of. Working on this API early doesn't mean we can't keep xul 
> based addons enabled longer than Firefox, but if we have to shut this done from one 
> day to another our addon community will probably be nonexistent.
> It is also a premier opportunity to work with the addons folks so that WebExtensions 
> doesn't turn into a second Addon-SDK that doesn't work well for Thunderbird.
> Philipp
> [1] 
> [2] 
> [3] 
> On 8/24/15 8:35 PM, R Kent James wrote:
>> We need to do some sort of announcement in the Thunderbird blog about our plans 
>> concerning addons. I'd like to have feedback from folks to see if there is any 
>> debate about what is the correct direction for us.
>> We've at least agreed that we are continuing to support binary addons. Concerning 
>> signing, we took steps months ago to not move forward on requiring addons to be 
>> signed, so there are no current plans to require signing. There is still some 
>> debate about that in bug 1168571. We should probably come to a firm decision and 
>> announce it. Most commenters were opposed to signing, though there were some holdouts.
>> Then there is "The Future of Developing Firefox Add-ons - The Mozilla Blog 
>> <>" 
>> that announces the complete disabling of current XUL addons at some point in the 
>> future. Several Thunderbird community members commented on that blog post, strongly 
>> opposed to that direction.
>> Contrast that with Firefox/Go Faster <> 
>> where there are plans to expand the use of addons in Firefox, adding so-called 
>> "system add-ons" and moving Hello to one. (This is similar to what we are doing 
>> with Lightning, which should hopefully make our Lightning integration easier in the 
>> future).
>> At this point, I think that the prevailing viewpoint is probably the following, and 
>> I would like to announce this if possible in a blog post:
>> 1)    Thunderbird continues to support binary addons.
>> 2)    Thunderbird will not require addon signing.
>> 3)    Thunderbird has no current plans to disable the use of traditional XUL/XPCOM 
>> addons in Thunderbird.
>> This policy must be modified by the caveat "as long as core Mozilla code can be 
>> used to support it".
>> (I might also note that initial patches are being looked at for the integration of 
>> the technology formerly know as Skinkglue into Thunderbird core, to be called 
>> JsAccount, which makes it possible to define new account types in Thunderbird using 
>> a traditional XUL/XPCOM/JavaScript addon. This will almost certainly be in our next 
>> major release).
>> Could I have some comments or discussion on these proposed positions?
>> I hope the Thunderbird community appreciates that diverging from Mozilla in this 
>> manner will probably mean that we will need to take over addon review from 
>> Thunderbird at some point, possibly including forking of AMO for our own use.
>> :rkent
>> _______________________________________________
>> tb-planning mailing list
>> tb-planning at
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