Add-on Compatibility for Firefox 42

Firefox 42 will be released on November 3rd. Here’s the list of changes that went into this version that can affect add-on compatibility. There is more information available in Firefox 42 for Developers, so you should also give it a look.

General

• Remove support for the prefixed mozRequestAnimationFrame.
• Convert newTab.xul to newTab.xhtml.
• Provide visual indicator as to which tab is causing sound. This required some changes to the tab XBL bindings, so it can break add-ons that change tab behavior or tab appearance.
• Badged button (like social buttons) causes havoc with overflow and panel menu. This was broken for a while, but it’s fixed now.
• Calling Map/Set/WeakMap() (without `new`) should throw.

XPCOM

• Split nsIContentPolicy::TYPE_SUBDOCUMENT into TYPE_FRAME and TYPE_IFRAME. This should only affect your add-on if it implements nsIContentPolicy.
• Use origin for nsIPermissionManager. Permissions in the Permission Manager used to be handled per-host, and now they will be handled per-origin. This means that https://mozilla.org and http://mozilla.org have different permission entries. This changes some methods in the Permission Manager so they accept URIs instead of strings.
• Update: nsINetUtil.parseContentType has been renamed to parseResponseContentType as part of a security fix. Its behavior should remain the same.

New

• Create API for add-ons to add large header image to speed-dial home panels.  This API is available for add-ons on Firefox for Android.

Please let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 42, I’d like to know.

The automatic compatibility validation and upgrade for add-ons on AMO will happen in the coming weeks, so keep an eye on your email if you have an add-on listed on our site with its compatibility set to Firefox 41.