Add-on Compatibility for Firefox 12

Firefox 12 will be pushed to the beta channel this week, meaning I’m late with my add-on compatibility report :(. Sorry for that, but other things have been taking my time. This won’t delay the Firefox 13 compatibility work, which I’ll begin right away.

Firefox 11 compat (addendum)

For more information about Firefox 11 compatibility, please read the full compatibility update.

Firefox 12

  • Remove the Jetpack service. Very old versions of the Add-ons SDK relied on this service in Firefox. Add-ons using this service must have been broken for a very long time anyway, so we encourage all developers to update the SDK version they’re working on. Visit our Developer Hub for more info.
  • The styling of the Customize Toolbar window could be improved. This shouldn’t break any extension, but if you add toolbar buttons or other widgets, it’s worth giving them a test. Themes are probably affected by this change.
  • Enable inline autocomplete again. Add-ons that tap into the location bar and its autocomplete / suggestions should check if anything breaks. Update: this ended up being shifted to Firefox 13.
  • addDownload should be made asynchronous. Quote: “Now users of nsIDownloadHistory cannot rely on the history entry to be present after the addDownload method returns. They should use nsINavHistoryObserver or another technique to wait for the target URI to be visited, if needed. The ‘link-visited’ observer topic cannot be used because it is notified before the history entry is saved.”
  • Remove sharp variables. This is a fairly obscure JavaScript feature, but it’s worth mentioning that it is gone now.
  • Rip out non-UniversalXPConnect privilege manager functionality. This mostly concerns web developers and intranet developers who request higher privileges for web content. The enablePrivilege function is being phased out and this is one step in that direction.
  • ‘chromemargin’ attribute changed behavior. A bug in the way the chromemargin attribute worked allowed some add-on developers to move around the minimize / maximize / close buttons. Recent changes in this code closed that bug and also break these add-ons. It doesn’t look like this change is going to be reverted, but some alternatives have been proposed in the bug.

 XPCOM Changes

Other important changes are noted in Firefox 12 for developers.

New Developer Features in 12

Coming Up in Firefox 13

These 2 points are big enough that they’re worth mentioning in advance:

  • New Tab Page feature. Firefox 13 will no longer show a blank page when you open a new tab. It’ll now show suggestions based on past activity. This overlaps with the features of several existing add-ons, so some breakage is to be expected. I would like to direct your attention to this bug: New Tab Page should be user skinnable. This is an apparently easy fix that would greatly help theme developers. If you have some time to work on this, please submit a patch. Update: note in the comments below that there may be a solution for the theme problem already.
  • Firefox 13 will have mandatory ASLR on Windows for binary components. Kyle Huey explains what this means in his blog.

Please let me know in the comments if there’s anything missing or incorrect on these lists.

19 comments on “Add-on Compatibility for Firefox 12”

  1. Kohei Yoshino wrote on

    I just posted the Japanese translation:

  2. Kohei wrote on

    According to Bug 566489, the inline autocomplete will be enabled in Firefox 13, not 12.

    1. Jorge Villalobos wrote on

      Yeah, you’re right. It’s updated now.


  3. patrickjdempsey wrote on

    I think I’m going to mark my bug about user-skinnable New Tab Page as resolved because of bug 729878 in which the main background of the New Tab Page was given the id #newtab-scrollbox which will mean after all of these years users will be able to apply userContent/Stylish hacks to the New Tab page!

    1. patrickjdempsey wrote on

      Actually looking closer it looks like #newtab-window should get everything.

      1. Jorge Villalobos wrote on

        Noted above. Thanks!

  4. Malcolm O’Callaghan wrote on

    It would be nice if the “Remove XPCOM proxies.” change specified some concrete strategies for replacing nsIProxyObjectManager, especially in native code.

    1. Jorge Villalobos wrote on

      The MDC has a useful link: Making cross-thread calls using runnables.

      Does this help?

  5. Charles wrote on

    I’m Getting tired of you guys forcing incompatibility of add-ons. Even Nightly and Compatibility Reporter are now incompatible. Please Stop it or make it easy to bypass this crappy feature.

  6. Ric wrote on

    Add on compatibility for Firefox 11 seems gone. I used it in earlier versions to keep Google toolbar. I can’t find out how to get the toolbar back–please don’t tell me I don’t want it. I know what I want and it is the Google toolbar. Thanks.

    1. Jorge Villalobos wrote on

      The Google Toolbar was discontinued since Firefox 4, so it is intentionally incompatible. This is Google’s decision, not ours, and you either need to find alternatives or be stuck with an older version of Firefox.

  7. Ana wrote on

    Hi, I am having problems with an extension that worked in previous versions of firefox 11. The problem is to load the java classes. From what I read, the method SIMILE seems to be obsolete in firefox 11, is there a new way to import Java classes? An suggestion or coment will be more than welcomed… Thank you very much!!

  8. Techie Sab wrote on

    My system getting slower while using Firefox.I happen to see ‘plugin container’ taking big amount of memory, when i opened Taskmanager- process.

    How can i get rid of this????

    1. Jorge Villalobos wrote on

      This means that you have a plugin that is consuming lots of memory, most likely the Flash plugin. Do you have many tabs open with Flash content in them? How about animated Flash advertisements? Some of those are poorly coded and can accumulate memory over time.

  9. Stephanie wrote on

    Half of my add-ons won’t work with version 12. A couple of them are pretty important. I can’t print anything because it is not compatible with HP detect and HP Smart Web printing 4.60. I am a college student and need to be able to print things. Also my Kaspersky URL Advisor They were compatible with the version 11. If you all can’t not fix these problems, then I will have no choice but to find a new browser. I would rather not do this. I have loved firefox up until this point. I have been using it for 7 years but this is ridiculous. The ability to print and be safe on the internet is a most for me. Please let me know if you will be able to fix these problems.

    1. Jorge Villalobos wrote on

      You’ll need to check for updates for your HP and Kaspersky software. It’s their responsibility to keep their add-ons up to date with the most recent release version of Firefox, but I recognize that it can be quite a challenge for them.

      One of the reasons we update Firefox this often is to keep you safe on the Internet. Unfortunately that comes at the cost of some third-party software breaking every time an update is released. While I think we have done a pretty good job when it comes to add-on compatibility, there’s a big category of add-ons that need to update every time, and they often end up updating fairly late.

      Finally, I’m surprised that you need an add-on in order to print. I find that very strange. You should be able to use the regular print dialog and your computer should be able to detect your HP printer. Are you sure you can’t print without it?

  10. Richard C wrote on

    Hi Jorge – I’m confused:

    I’m definitely running FF 12.0. Also, I’m pretty sure I’m running the Google Toolbar.
    This isn’t possible, right?

    Or is it just because I’ve disabled compatibility checking?

    Thanks, Richard

    1. Jorge Villalobos wrote on

      You must have disabled compatibility checking, yes, because Firefox should be telling you it isn’t compatible. Google stopped supporting it a while ago, and while most of its features should continue to work, some of them should be broken by now.

  11. luigi lutini wrote on

    il firefox 12 non compatibile con il 13 perche