Version 2 of the browser preview, which works only on Windows Vista- and Windows 7-based machines, can be downloaded from Microsoft's test site here. Like its predecessor, this prototype lacks the basic features of a browser, such as an information bar. It also lacks basic security protections for Web browsing built into Internet Explorer 8.
Users can install IE 9 platform preview alongside Internet Explore 8 without conflict, according to Microsoft's announcement on its IE Blog. The installation will overwrite the first version of the preview. Microsoft announced the first version of the preview back in March at its MIX 10 Web developer event. At that time, the company announced plans to release updates to the preview about every eight weeks.
Microsoft is rolling out this second version after fixing some earlier bugs, but platform preview No. 2 also includes some customer-requested features. One of those features is CSS3 Media Query support, which allows the browser to rapidly change display attributes, such as the display's width and height, adapting to the different screen sizes of desktop PCs, netbooks and mobile devices.
Another requested feature added to the new IE 9 platform preview is DOMContentLoaded, which makes content available to users after the page parses, rather than waiting for everything to load. The point is illustrated in a Microsoft Channel 9 video by Tony Ross, a program manager for Internet Explorer. Microsoft's best-practices advice to developers, according to Ross, is to test for Worldwide Web Consortium (W3C) HTML 5 standards support and features support first, and include fallback measures when those standards and features aren't supported by the browser.
Microsoft has heavily emphasized that IE 9 will tap into the hardware acceleration capabilities of graphics processing units in PCs, taking advantage of native scalable vector graphics (SVG) support enabled by the HTML 5 specification. A video (Windows Media Player file) illustrates some of the tests Microsoft has devised. Developers can check the availability of SVG support for custom-built pages using the FeatureDOMmethod function, as explained by Patrick Dengler, senior program manager for Internet Explorer, in a Channel 9 video.
Sharon Newman, a program manager for Internet Explorer, pointed out in another Channel 9 video that browsers already interpret the HTML 5 spec differently. In her demo, she noted that practically speaking, the Mozilla Firefox and Apple Safari browsers don't support the W3C's recommendations for displaying rounded corners on an object. Moreover, even though the Google Chrome browser uses the same WebKit rendering engine as Safari, the two browsers showed different results on Microsoft's HTML 5 rounded corners test.
Developers with a bad memories of having to code specifically for the quirks of the IE 6 browser may be surprised by all of Microsoft's talk of standards with IE 8, and now with IE 9. However, Dean Hachamovitch, general manager of Internet Explorer, explained in the IE blog that Microsoft is aiming for a code once and render the same way in different browsers-type approach. He also suggested that the speed improvements showing up in IE 9 tests using HTML 5 and hardware-accelerated graphics will happen without a code rewrite by Web developers.
"What's particularly exciting is that developers don't have to rewrite their sites -- their current markup (HTML, CSS, and script) just runs faster," Hachamovitch wrote in the blog.
In the long term, IE 9 represents a break from the past of having to paste browser-sniffer code in Web pages. Developers will not necessarily have to use detection methods for various IE browser versions, at least in IE 9's case.
"IE9's standards support makes it much closer, for developers, to Gecko, Presto, and the different versions of Webkit than it is to IE7," Hachamovitch explained.
Microsoft has been submitting test cases to W3C committees to ferret out different interpretations of the still-evolving HTML 5 spec. The spec still awaits ratification as a standard, which may not happen for 10 years, according to a Forrester Research report.
Hachamovitch explained that Microsoft added 88 new tests to the W3C's working groups on Wednesday. During its IE 9 development phase, Microsoft has submitted a total of 192 tests to the W3C. The company previously submitted more than 7,000 tests to that body when it was developing IE 8.
A full list of the changes in the new IE 9 platform preview is described in Microsoft's release notes here. Microsoft didn't disclose when a beta release of IE 9 would become available.
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