Mozilla has released the fifth Alpha for Gecko 1.9.3 layout engine likely to be used in the future Firefox 4. This release is being made available for testing purposes only, and is intended as a preview release for web application developers and the testing community. See Release Notes for more information and download/installation instructions. New changes in this release include:
- 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.
- 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.
- An updated
about:memorypage 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.
Source: Mozilla Developers News