Mozilla Corp. unveiled the final beta of Firefox 3.0 on april 2 2008 and will move on to the release candidate stage by freezing changes as early as next week.Firefox 3.0 Beta 5 landed on Mozilla’s download servers early on the 2 April’s afternoon.

Mike Beltzner, Mozilla’s interface designer, highlighted several changes to the open-source browser. Among them are improved UI integration with the underlying operating system, performance gains from additional changes to the JavaScript engine, and an unspecified number of bug fixes and modifications for features new in Firefox 3.0, such as full-page zoom and bookmark backup and restore.

Beta 5’s release was delayed somewhat by the discovery last week of a serious bug in the Mac version of the browser, which required fixing before Mozilla would sign off on the preview.

Updated release notes also published on that day noted that Beta 5 includes more than 750 changes since the rollout of Beta 4 about three weeks ago. That day’s beta will be the last for Firefox 3.0, Mozilla’s chief engineer has said, and developers will be moving on to Release Candidate 1.

Mike Schroepfer, Mozilla’s vice president of engineering, said last week that he expects Firefox 3.0 to run through three release candidates before the final version. Mozilla has targeted June for delivering the browser.

Firefox 3 Beta 4 can be downloaded for Windows, Mac OS X and Linux in 40 languages from Mozilla’s site.

However, as has been its practice with every beta, Mozilla again warned casual users against using the preview. “Firefox 3 Beta 5 is a developer preview release of Mozilla’s next generation Firefox browser and is being made available for testing purposes only,” the release notes read.