Dec 30, 2010 13:05 GMT  ·  By

Firefox 4.0 may still be at least a couple of months away, but progress is being made. The latest betas are quite close to the finished product and Mozilla is encouraging developers to update their add-ons for Firefox 4.0 compatibility. It's doing more than encouraging in fact, it's actually 'bribing' developers with a free t-shirt for the ones that manage to update their add-ons by January 7.

"Firefox 4 is coming very soon, and it’s now time to start marking your add-ons compatible with 4.0.*. We don’t expect any further compatibility-breaking changes in Firefox 4 betas, and any that do need to land will be announced on this blog, on MDC, and via email if we can identify AMO-hosted add-ons that are affected," Mozilla announced.

"We will continue to add beta versions as they are released, but most add-ons should now begin to use 4.0.* as their maxVersion," it added.

Granted, Firefox 4.0 has been in feature freeze for a while now. The add-on APIs are mostly complete as well and, though there will be updates and changes, none should break compatibility at this point.

Therefore, Mozilla is asking developers to start thinking about add-on compatibility with Firefox 4.0. This has always been an issue for Firefox, each major update comes with broken add-ons.

In many cases add-ons would work perfectly fine on the newer versions of the browser, but if they are not updated by their creators they will be listed as incompatible regardless.

In order to prevent a massive number of incompatible add-ons when Firefox 4.0 does eventually roll out, there is an effort to get developers involved early.

And, if simple persuasion doesn't work, Mozilla is prepared to go one step further and is offering a free t-shirt to any developer that provides an updated add-on compatible with Firefox 4.0 or Firefox 4.0 Beta.