The platform preview is not a complete browser since it lacks an address bar and some navigation and security features. It's a prebeta release that shows off the IE team's integration of HTML 5 support, scalable vector graphics and hardware-accelerated graphics -- all hallmarks of Microsoft's technology focus with IE 9.
Platform preview 4 of IE 9 can be downloaded at Microsoft's test page here. It runs on Windows 7 and Windows Vista, but it doesn't work with Windows XP.
Dean Hachamovitch, general manager of Internet Explorer, said that this latest IE 9 platform preview is "nearly complete" in a blog post. He asked that designers, developers and partners begin testing platform preview 4 to get ready for the forthcoming beta version. Kevin Turner, Microsoft's chief operating officer, recently said that IE 9 will be released as a beta sometime in September.
Platform preview 4 will be the last test platform issued before the beta release of IE 9.
"Through this deep integration, the performance of real world websites significantly improves, and IE9 becomes the first browser to have a shared DOM [Document Object Module] between the browser and the script engine based on ECMAScript5."
Microsoft's main goal with IE 9 has been to unburden developers from having to code for different browsers. In most cases, developers have been coding for quirks based on legacy browser performance, particularly Internet Explorer 6, which is still widely used. Microsoft is now advocating that developers should code for features to take advantage of them when they get supported in browsers. That approach also helps to avoid potential display problems that can occur as browser makers issue various versions of their products.
With the platform 4 release, Microsoft has rolled out new tests. They allow users to compare IE 9 performance with that of other browsers. An overview of the tests is described by Rob Mauceri, group program manager for Internet Explorer.
Josh Rose, program manager for Internet Explorer, shows how hardware acceleration affects audio performance in IE 9 platform preview 4. Patrick Dengler, senior program manager for Internet Explorer, demonstrates scalable vector graphics performance. Native graphics support for the canvas element is demonstrated by Seth McLaughlin, program manager for Internet Explorer.
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