Mozilla has released a new beta for Firefox 4 for testing.

This new beta (Beta 2) now has support for 23 different languages and also an ability of turning tabs into App Tabs. The Tabs on top feature has now been extended to Mac OSX users as well.

Some of the Feature Highlights of Firefox 4 Beta 2 are:

• Tabs on Top is now available for both Windows and Mac users.
• For Windows Vista/7 users, the Menu bar has replaced with a single Firefox button, so that users get to the most used options with just a single click.
• Support for App Tabs which offer a better way to manage your frequently used tabs thus saving space on the tab bar. (Video Demo).
• CSS3 Transitions: Firefox 4 Beta now has support for new CSS3 features like Transitions and Transformations etc. (Video Demo)
• Retained Layers for for super-fast scrolling on complex websites.
• Changes to XPCOM Framework to improve the start up time of Firefox.

For a detailed changelog, check out the release notes.

Download Firefox 4 Beta 2.

[Firefox Blog]