Mozilla releases fourth Firefox 4 beta

Less than two weeks after beta 3 and following a one day delay, Mozilla has announced the release of the fourth beta for version 4.0 of its Firefox web browser. According to Firefox development director Mike Beltzner, the latest development preview adds several new features that give users more control over their web experience. 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.

Firefox 4 Beta 4 on Mac OS X. Firefox 4 Beta 4 features the default inclusion of Firefox Sync – formerly known as Weave – for synchronising user bookmarks, passwords, preferences, forms, history and open tabs between Firefox installations running on different PCs or on mobile devices. The fourth beta also introduces a new feature called Firefox Panorama, previously called Tab Candy. With support for groups, Panorama provides a new way for users to manage their tabs by zooming out of the current browser tab to view a grid of thumbnail images for each open tab.

Unlike the 3.6 branch of Firefox which uses Gecko 1.9.2, version 4 is based on version 2.0 of the Gecko rendering platform and has a new Add-ons Manager and extension management API. New features for web developers include support for the HTML5 video “buffered” property, an experimental API aimed at providing more efficient JavaScript animations and an experimental CSS extension for drawing arbitrary elements as backgrounds. Other changes include replacing the HTML5 video “autobuffer” with "preload", increasing the default disk cache size from 40 MB to 250 MB and various bug fixes.

According to the Mozilla Platform Meeting Minutes, the Beta 5 code freeze is currently set for this Friday and it should go to build on Monday. The feature freeze has been moved to the sixth beta aimed at the 10th of September. A first release candidate (RC) for Firefox 4 is currently scheduled to arrive in October of this year. However, the final release date 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, on the official Firefox 4 beta site and in the official release announcement by Beltzner. Firefox 4.0 Beta 4 is available to download for Windows, Mac OS X and Linux. Alternatively, existing Firefox 4.0 Beta 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 end of July.

See also:

• Firefox 4 to include silent update system, a report from The H.
• Mozilla's Beltzner announces Firefox 4 plans, a report from The H.
• Firefox and the open web, a feature from The H.

(crve)