Firefox 25 will be released on October 29th. Here’s the list of changes that went into this version that can affect add-on compatibility. There is more information available in Firefox 25 for Developers, so you should read that too.
- Update: Status panel should be attached to the content area without overlapping surrounding chrome. I didn’t learn about this change until it was brought up in the comments below. If you get the status panel using
getElementById("statusbar-display"), it won’t work anymore. You need to
- Improve the visual appearance of the “find in page” bar. This is part of a major overhaul in the find bar. If you add-on depends on that binding, you’ll want to keep a close eye on this and future updates. This new version makes the find bar show up in the content area instead of at the window level (try opening a sidebar to see the difference), and it might also be moved to the top in the future (it briefly appeared at the top in the Aurora channel, but it was rolled back).
- Use asynchronous getCharsetForURI in getShortcutOrURI. This replaces the
getShortcutOrURIfunction with the asynchronous
getShortcutOrURIAndPostData. This also affects the function
_canonizeURLfrom urlbarBindings.xml, making it asynchronous as well.
- Remove support for binary annotations.
- Stop exposing nsIDOM* interfaces on the global automatically. This cleans up several chrome-specific interfaces that were being exposed to content. There’s a comprehensive list of the removals in this article.
- preventDefault on keydown does not cancel following keypress. It now does, which we know affected at least one add-on.
- Fix up our XBL1 shadow tree implementation. This made a series of back-end changes to XBL, which should be generally invisible. This briefly broke complex add-on toolbar buttons, though, but that is fixed already and no change is required from developers as far as I know.
- Clean up SessionStore initialization. This shouldn’t affect add-ons unless they manually call
SessionStore.init(), which they shouldn’t. However, if your add-on does, you might want to read comment 10 and the following ones.
- Remove “profile” database from OpenSpecialDatabase.
- Move IDBTransaction, IDBRequest, IDBCursor to WebIDL. This is part of the moving of IndexedDB away from XPCOM, which is slated to be finished in Firefox 27.
- Add a CSS Media Query for Windows 8 Desktop theme. The outcome of this bug is that there’s now a -moz-os-version selector that can make things easier for theme and extension developers.
Please let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 25, I’d like to know.
The automatic compatibility validation and upgrade for add-ons on AMO will happen in the coming weeks (the Mozilla Summit will probably delay this), so keep an eye on your email if you have an add-on listed on our site with its compatibility set to Firefox 24.