What's all this about sunsetting Tab Center?

I see in the changelog that Tab Center will “sunset” with Firefox v55. Does that mean Tab Center will become a standard feature of Firefox? Or should I start looking for another sidebar-tab add-on?


I too would like to know because to be honest, you’ll probably not find anything that comes close to Tab Center. Kudos Mozilla! Please keep it.


The Test Pilot page says “Firefox is changing fast. Tab Center may have bugs in Firefox 55 and will be disabled completely in Firefox 56+.”

There’s also a ticket in Tab Center’s issue tracker that mentions Tab Center Redux as the likely future of the project, although that doesn’t seem to be an actual working thing yet.


I found a WebExtension-based tab sidebar addon called Tree Tabs, but Nightly 56 won’t install it from AMO for some reason, claiming “it appears to be corrupt”.

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I understand the experimental nature of Test Pilot, and I’m painfully aware of the 57 milestone, but I’m shocked by:

  • the likelihood of issues with 55
  • the certainty of the experiment ceasing to work with 56.

Until yesterday, I assumed that current Test Pilot experiments were developed with 57+ in mind.

Has Firefox changed the goalposts in some way, to cause issues to arise so much sooner – 55?

Re: the end-of-life (EOL) area on the test initiator journey

– please, can someone refer us to relevant reports?

Please note, this is not a criticism of @bwinton or other contributors to the experiment. I am more broadly concerned by the directions of Firefox.

Tab Center started development over a year ago, and the WebExtension APIs that are the future of add-ons hadn’t been created at that point, so we chose to base it on older technology, knowing that it would probably become obsolete sooner, but also knowing that it was an short-term experiment, and that this implementation was never intended to land in Firefox. I mention this as an example to illustrate that many of the early Test Pilot experiments weren’t developed with 57+ in mind, and it wouldn’t have made much sense to do so. The newer experiments (as far as I know) are being developed in a way that will let them continue working far into the future.

Last year, I didn’t expect that there would be a lot of issues with Firefox 55 or 56, but since we started working on the Photon UI refresh, we have been landing a lot of changes into Nightly, because it’s a bigger job than just one release, and it is those changes that have been breaking Tab Center. My understanding is that most of them won’t make it to Beta until 57, so we may enable support for 55, or even 56 when those reach Beta, depending on how well it works at that time. I don’t see it as a matter of changing the goalposts, as much as the product going through some massive improvements, and Tab Center not being able to keep up.

I truly believe that, painful as it is (also for me!), these breakages are indications of great things coming to Firefox, and I wouldn’t be concerned. I’d also like to take this opportunity to thank all of you for your support and suggestions. Tab Center is one of the highlights of my time on the Firefox team, and you all are part of the reason why. :slight_smile:


Thanks for the clarification and reassurance :thumbsup:

(I should probably also say that I’ve moved to Tab Center Redux, and have even contributed a patch already. I think it will probably be a good replacement in the not-too-distant future, if not already.)

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It’s no longer for 54, the version to which I’m limited on FreeBSD, but I greatly appreciate the direction – and all contributions!

After suffering for a few hours with messed-up viewss of things (I assumed an extension conflict), I wasted time with a refresh of Firefox (never a refreshing experience, I must say), then signed in, synced, slept … awoke and wondered why all things Test Pilot-related were missing.

So I guess that Firefox Sync excludes Firefox Test Pilot.

Eventually I realised that sunset has occurred for the Tab Centre experiment. Sooner than I expected – I’m still on Firefox 54.0.1 (64-bit).

I had forgotten how ugly it is to have tabs forced on top. This is far from a positive ‘graduation’ experience :frowning:

Agreed. The lack of support for this is baffling.

I switched to Vertical Tabs Reloaded:

Nice, but not compatible with Tab Groups.

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