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I briefly blogged earlier this year about our internal project that allowed us to write Firefox extensions using the Google Web Toolkit framework. I’m happy to say that I’ve just pushed out the first version of the code for developers to start playing with.

Building a Firefox extension isn’t much different than writing a standard GWT web application. There are some caveats: there isn’t a global window ($wnd) or document ($doc) and the GWT widget system doesn’t work without some tweaks. You can, however, take advantage of GWT’s extensive DOM bindings to manipulate pages that the user loads and interact with the Chrome DOM to add toolbar buttons and menu items. I’m slowly working on extracting the code to work with these browser elements from our proprietary codebase, cleaning them up and pushing them into the open-source project.

For now, the current version of gwt-firefox-extension should be sufficient to write an application with the same functionality as a greasemonkey script without dipping into more advanced concepts. We’ve also generated bindings for the whole set of XPCOM IDL, so you’ll have access to most every service and component in the browser if you need to do something more complicated.

Try it out and join our open-source mailing list if you’ve got any feedback or suggestions.