Firefox 9 doesn't have a lot of changes that should be compatibility issues for add-on developers. However, there are a few possible items that might trip you up, so let's take a look.
Do you need to do anything at all?
If your add-on is distributed on addons.mozilla.org (AMO), it's been checked by an automated compatibility verification tool. Add-ons that don't use APIs that changed in Firefox 8, and have no binary components (which need to be recompiled for every major Firefox release), have automatically been updated on AMO to indicate that they work in Firefox 9.
So you should start by visiting AMO and looking to see if your add-on needs any work done at all.
Once you've confirmed that you need to make changes, come on back to this page and read on.
Bootstrapped add-ons can remove delayed-load scripts
If your add-on uses
nsIChromeFrameMessageManager.loadFrameScript() with the delayed-load flag set, the script gets loaded into every frame created from that point on. This is great, except that until Firefox 9, there was no way to stop loading the script, so it would keep happening even after your add-on was shut down.
Starting in Firefox 9, you should call the new
nsIChromeFrameMessageManager.removeDelayedFrameScript() method to stop loading your script in newly-created frames. You do this like this, for example:
nsIURLinterface has been changed a bit. The
nsIURL.paramattribute was removed, and the
nsIURLParser.parsePath()method has two fewer arguments than it did previously.
- Two methods have been removed from
unregisterOpenPage(). These methods had been deprecated.
nsIEditorSpellCheck.saveDefaultDictionary()method has been removed as part of supporting per-site spell check settings. Also,
nsIEditorSpellCheck.updateCurrentDictionary()no longer takes a parameter.
nsIGlobalHistory3interface has been removed. Its functionality was of limited (if any) use to add-ons, so this shouldn't affect anyone.
- Several specialized channels' properties attributes have been merged into the base
nsIChannelinterface. This shouldn't affect compatibility at all, since those interfaces inherit from
geo.wifi.* preferences no longer have default values, although they're honored if they exist. If your code reads these without handling the case where they don't exist, you need to update your code to handle the exception that gets thrown when they're not present.
baseURIObject have been moved from
XrayWrapper. This shouldn't affect many add-ons, since it would only be an issue if they try to access these properties on DOM
Node objects from unprivileged script that have requested XPConnect privileges using
- The long-obsolete method
Navigator.taintEnabled()has been removed. This hasn't done anything useful in a very long time, but was often used in browser detection scripts, since it was Netscape-specific. Calling this method throws an exception starting in Firefox 9.
- Event handlers are now implemented as standard IDL interfaces. For most cases, this won't affect you, but there are exceptions.
Other changes that may affect binary compatibility
These changes are notable in that they may affect binary XPCOM components. These will need rebuilding anyway, since that's required for every major release of Firefox, but could introduce compile-time errors, so they're worth noting in particular.
nsIDOMHTMLDocumentinterface now has a new
scriptsattribute, which implements the
nsIJumpListShortcut.iconImageUri()method has been added, to make it possible to establish favicons on jump list URI entries on Windows.
pending attribute has been added to the
<xul:tab> element. If this attribute is present, the tab is in the process of being restored by the session store service. You can use that to style the tab during the restore process. It's worth noting that if the user has turned on the "Don't load tabs until selected" preference, the
pending attribute is set on tabs until they get loaded.
Similarly, tabs also now have an
unread attribute; this property, if present, indicates that the tab has changed since the last time it was the active tab. You can use this to style tabs differently when they have changed since the last time the user looked at them. This is also present on tabs that have not yet been looked at during the current session.