According to the initial plans regarding the evolution of version 3.0 of its open source browser, there was supposed to be no pit stop between Release Candidate 2 and the final build. And the fact of the matter is that as far as the Windows and Linux platforms are concerned this is the case. Mac OS X, however, is the exception to this rule. While working to finalize Firefox 3.0 for a mid-June 2008 launch, Mozilla also gets ready to introduce Firefox 3.0 Release Candidate 3. The RC3 build is also available for Windows and Linux, but it is nothing more than the RC2 version, with a new label.

"Firefox 3.0 RC3 is a new build for Mac only, picking up the fix for Bug 436575. Both Linux and Windows builds are unchanged from the RC2 that was already released", Mozilla stated in a note accompanying the release. Bug 436575 is an issue affecting not only Firefox 3.0 for Mac, but also Firefox 2.0. According to Bugzilla, the bug prevents Mac OS X machines from shutting down and also the users from closing Firefox. As of RC3 the problem has been resolved.

Mozilla has posted nightly builds of Firefox 3.0 RC3 on its FTP servers, but they are just pre-RC3 versions and not the full Release Candidate. It is unclear at this time how RC3 will affect the general availability of Firefox, but it is likely that the impact will be only superficial. This mainly because Mozilla is determined to ship Firefox 3.0 in no more than a couple of weeks.

One of the aspects that were overlooked on the way to the final version of Firefox 3.0 was compliance with the Acid3 test. As of RC2, Firefox 3.0 scores a maximum of 71 out of 100, as you can see from the image on the left. But the open source browser continues its way to deliver full support for modern web standards having grown a full five points since previous releases.

"Now that mozilla-central, the source code repository for the release of Firefox after 3.0, is open, a bunch of patches fixing bugs affecting our score on the Acid3 test have landed. We pass test 30 since we now allow DOM events to be dispatched multiple times. We pass test 38 since we now implement the replaceWholeText method and the wholeText attribute from DOM Level 3 Core. We pass test 39 since we now implement the :nth-*() selectors. We pass test 40 since we now implement the :*-of-type selectors. We now pass test 68 (and show the results correctly when Shift-clicking on the A) thanks to a UTF-16 surrogate handling fix", Mozilla explained.

Firefox 3.0 RC2 is available for download here.