Mozilla releases second Firefox 4 beta

Following a short delay, the Mozilla development team have announced the release of the second beta for version 4.0 of their Firefox web browser. According to Firefox development director Mike Beltzner, the latest development preview is aimed at providing an early look at what’s planned for the browser update. Firefox 4 will be the next major release of Mozilla's popular open source browser and will include a number of improvements, updates and new features; both for end users and developers.

As previously announced, Firefox 4 Beta 2 includes the new 'tabs on top' layout – similar to the tabs position in the Chrome and Opera web browsers – for Mac OS X systems and is now available in 23 languages. The new layout was initially introduced in the first Firefox 4 beta earlier this month, but only for Windows-based systems. The developers say that they moved the tabs to "make it easier to focus on the Web content" and note that Linux systems will receive the new tabs on top layout in a future update "when the theme has been modified to support the change".

Firefox 4.0 Beta 2 on Mac OS X. Changes affecting developers include support for new for CSS transitions, a new Cascading Style Sheets (CSS) technology feature that provides a way to animate changes rather than having the changes take effect instantly. Further information about CSS3 transitions, including a demo, can be found in a post on the Mozilla Hacks blog by Paul Rouget. Other changes include the addition of retained layers, allowing for "super-fast scrolling" on complex web sites and changes to the XPCOM framework that improve start up time.

Firefox 4 is based on version 2.0 of the Gecko rendering platform – the Firefox 3.6 branch uses Gecko 1.9.2 – and features a new Add-ons Manager and extension management API. Beltzner says that the developers plan to release a new beta version "every two to three weeks". A first release candidate (RC) for Firefox 4 is currently scheduled to arrive in October of this year. A final release date, however, has yet to be confirmed.

While the developers note that they consider the release to be "stable and safe to use for daily web browsing", use in production environments and on mission critical systems is not advised. Users testing the release are encouraged to provide feedback and report any bugs that they encounter.

More details about the release, including a list of known issues, can be found in the release notes and in the official release announcement by Beltzner. Firefox 4.0 Beta 2 is available to download for Windows, Mac OS X and Linux. Alternatively, Firefox 4.0 Beta 1 users can upgrade to the new version, either by waiting for the automated update notification or by manually selecting "Check for updates" from the Help Menu.

Firefox binaries are released under the Mozilla Firefox End-User Software License Agreement and the source code is released under disjunctive tri-licensing that includes the Mozilla Public Licence, GPLv2 and LGPLv2.1. The latest stable release of Firefox is version 3.6.8 from the 23rd of July.

See also:

• Mozilla releases Firefox 3.6.8 to close critical vulnerability, a report from The H.
• Mozilla's Beltzner announces Firefox 4 plans, a report from The H.

(crve)