Firefox 17 was released yesterday, and there a couple of notable compatibility issues that have surfaced and are worth pointing out.
Tab Mix Plus currently incompatible
The popular Tab Mix Plus extension is causing some problems for users in Firefox 17. The problems include broken menu items – like the one that opens the Add-ons Manager – and broken links in Firefox windows, like the About dialog.
This extension broke due to bug 761723, and a fixed version hasn’t been released to AMO yet. Apparently there’s a development version of Tab Mix Plus that fixes these issues, so hopefully it will be pushed to the general public soon.
In the meantime, we recommend users to disable the add-on until the new update is released.
toString() compatibility warning
We ran the automatic compatibility upgrade last week, emailing developers who have add-ons on AMO about their compatibility status. This included a warning for using eval and the Function constructor, since these are often used to monkeypatch Firefox functions, and they most likely broke due to bug 761723.
This is the message that you should see if your add-on was flagged:
The `toString` implementation for function objects have changed. If you are using `eval` or `Function` to change the behavior of ‘native’ functions, it is probably not working correctly in Firefox 17 and above.
Unfortunately, this warning is appearing on many more add-ons that we intended. Notably, it will show up for all add-ons using the jquery library, or any other libraries that use eval of the Function constructor.
In these cases, you don’t need to worry about the warnings. They’re false positives and can be easily ignored. Also, even if you got a message from us indicating your add-on didn’t pass our compatibility checks, you don’t need to take any action for your add-on to remain compatible with Firefox 17 and above. Because of the Default to Compatible feature, all add-ons remain compatible, even if they don’t pass our checks. However, we always recommend that you test your add-on with every new release and make sure everything still works.
Binary compatibility briefly broken before release
We assure developers of binary add-ons that they can build their binaries based off of the first beta for every Firefox version. This gives them 6 weeks to have their add-ons ready before a new version is released to the public.
Unfortunately, we overlooked a change that broke binary compatibility in Firefox 17 beta 6. This was reported as bug 813264 and quickly fixed on Firefox 17 beta 7, which made it to release.
So, if you built your binary add-on based on the early Firefox 17 betas, you don’t need to do anything. If you built your binaries based on beta 6, you’ll need to rebuild them using beta 7 or the release version. We apologize for the inconvenience, and will look into ways to ensure this doesn’t happen again.