The fifth Mozilla Developer Preview (1.9.3 alpha)

Jun 16, 2010 14:33 GMT  ·  By

Earlier this week, Mozilla made available the fifth Alpha Build of Mozilla Developer Preview 1.9.3, which, despite being labeled Firefox 3.7, is in fact the first Alpha of Firefox 4.0, the next major version of the open source browser. Firefox 4.0 Alpha 1 is available for download not just for early adopters running Windows, but also for those running Linux and Mac OS X. At the same time, Mozilla has also released the first 64-bit (x64) Builds available for Mac and Linux. And just as it is the case with the 64-bit Firefox for Windows, all x64 flavors of the browser fail to play nice with existing 32-bit (x86) plugins. In addition to the lack of plugin support, including Adobe Flash, Mozilla noted that the 64-bit releases of Firefox were considered highly experimental.

There are consistent changes in Firefox 4.0 Alpha 1 (Developer Preview 1.9.3 Alpha 5) on the surface of the browser, but also in terms of web standards support and under the hood. Testers will easily be able to identify the modifications to the UI, with Firefox 4.0 being better tailored to Windows Aero in Windows 7 and Windows Vista.

At the same time, the evolution of Firefox 4.0 implies embracing additional web standards, such as the recently released WebM and VP8 HTML5 video codec. And there are additional changes, including a new page designed to display RAM consumption. Mozilla provided a list with the Firefox 4.0 Alpha 1 changes that I included at the bottom of this article. The plan is for the first Beta development milestone of Firefox 4.0 to be offered to testers by the end of this month.

Firefox 4.0 Alpha 1 (Developer Preview 1.9.3 Alpha 5) changes:

User-facing changes

“- Aero Glass is now enabled for Windows Vista and Windows 7. - More parts of the new Windows theme have landed including new main button icons. Many more changes are coming in later releases. - The new Add-ons manager has landed. The UI for the new Add-ons manager is not yet complete. - You can now put tabs on top (View -> Toolbars -> Tabs on Top) although without most of the final UI this isn’t as useful as it could be.    

Web-facing changes

“- Support for WebM is included with this build. (Try an example video on Youtube.) - When viewing HTML5 videos in full screen, we now use hardware acceleration for Windows (DX9) and Macs (OpenGL). - This is the first release of any browser that has proper support for parsing HTML5 according to the specification.  - This build has early support for some HTML5 forms. - We now support the FormData interface, part of XHR level 2 spec. - We now support a Mozilla-specific CSS selector: -moz-any. Please see the post for examples, but this will be very useful in HTML5 contexts. - We now do Lazy Frame Construction which can vastly improve the performance of complex pages that add large numbers of elements to a page. - Lots of new JavaScript performance improvements have been made.

Platform Changes

“- An updated about:memory page shows you how memory is being consumed in the browser. This will improve with later updates to give even more useful data and cover more internal memory pools. - On the Mac we now support the Cocoa event model for NPAPI plugins. This is used by Flash 10.1 and the new Java plugin from Apple.- ChromeWorkers with jscytpes is now supported.”  

Firefox 4.0 Alpha 1 (Mozilla Developer Preview 3.7 Alpha 5) is available for download here.

Opera 10.60 Beta with HTML5 WebM VP8 video support is available for download
here.

Google Chrome 6.0.427.0 WebM/VP8 Dev is available for download
here.

Internet Explorer 9 (IE9) Platform Preview 2 Build 1.9.7766.6000 is available for download
here.

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