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The new update of Firefox 4 Beta is now available in 23 languages for testing and feedback. Thanks to the help of the global Mozilla community, we’re now able to bring Firefox 4 Beta to more people around the world. This update to Firefox 4 Beta continues with changes to the look of Firefox with tabs appearing on the top of the browser and introduces the ability to turn tabs into App Tabs.

What’s new in this Firefox 4 Beta update?

Continued Evolution of the New Firefox Look – Tabs on Top

Mac and Windows users now have all their tabs on the top of the browser. We moved the tabs to the top to make it easier to focus on the Web content and easier to control the tools in your Web browser.

If you have Windows 7 or Windows Vista, the Menu bar is replaced with a single Firefox button so you get to the most used options with just one click.

App Tabs

There are some websites you visit many times throughout your day, such as your email, social networks, music or game sites. Now you can turn the websites you use most into App Tabs to easily find the ones you need.

App Tabs offer a better way to manage tabs, saving space on the tab bar and making it easy to find frequently used tabs. Check out this video from Alex Faaborg for more details on App Tabs.

New for Developers: Under the Hood

CSS3 Transitions:

The Firefox 4 Beta now has support for new CSS3 features like Transitions and Transformations, making it fun to add elegant animations to your websites.

To show what CSS3 Transitions can do, we added them to the Firefox 4 Beta “What’s New” page. For more information, check out this post and demo from Paul Roget.

Retained Layers:

Adding Retained Layers in Firefox 4 Beta allows for super-fast scrolling on complex websites. See Robert O’Callahan’s post for more information.

XPCOM Framework:

We made changes to the XPCOM framework that improves start up time when you load Firefox. See Jorge Villalobos post for more information.

There are more features to come in future Firefox 4 Beta updates and we need your help to test them. Already with help from our community of testers, we were able to get valuable feedback on the first Firefox 4 Beta that enabled us to fix more than 670 issues in this update.

Help build the best Firefox ever!

Firefox 4 Beta includes a new Feedback Add-on so at any time you can click the Feedback button to tell us about what you do or don’t like. The Feedback Add-on includes Mozilla Labs Test Pilot, and will ask you to take part in anonymous studies. The latest Test Pilot study explores the ways people interact with the Firefox menu bar, Firefox button (on Windows Vista and 7) and toolbar controls. You can choose to opt-out of any or all studies and manage your settings in the Feedback button (no data will be sent to Mozilla without your permission).

Testers will receive automatic updates to the Firefox 4 Beta, so stay tuned for the next release in the coming weeks.