Firefox 13 has been in beta for a while now, so this blog post is a bit overdue. Here’s an almost comprehensive list of the changes that went into Firefox 13 that can affect add-on compatibility. There is more information available in Firefox 13 for Developers, so you should read that too.

General

XPCOM

Merge nsIPrefBranch2 with nsIPrefBranch . The very commonly used nsIPrefBranch2 is now deprecated. If you have preference observers, you’re using this interface. It still works as it always has and there are no plans to drop it in the near future. However, it’s best that you begin moving away from it.

. The very commonly used nsIPrefBranch2 is now deprecated. If you have preference observers, you’re using this interface. It still works as it always has and there are no plans to drop it in the near future. However, it’s best that you begin moving away from it. Mandatory ASLR on Windows for binary components . This is very important if you have binary components. My understanding is that the default compile options include ASLR, but you should still verify that your components load correctly. More details in this blog post.

. This is very important if you have binary components. My understanding is that the default compile options include ASLR, but you should still verify that your components load correctly. More details in this blog post. Merge nsIAccessNode and nsIAccessible. nsIAccessNode no longer exists.

Remove FileError. nsIDOMFileError no longer exists.

New!

Please let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 13, I’d like to know.

We will be doing an automatic compatibility validation and upgrading for add-ons on AMO that are compatible with Firefox 12, sometime in the next 2 weeks. I’ll also be working in Firefox 14 compatibility so that it doesn’t come in as late as this one.