Windows 8 Release Preview includes the sixth release preview of Internet Explorer 10. After several years of beating the drum of standards compliance and freedom from plugins, Internet Explorer 10 has surprised many with the integration of Adobe Flash. That's not the only provocative change the new browser makes: it enables Do Not Track by default, too. Standards compliance has also been further improved, and there are one or two interesting new usability features.

As previously reported, Internet Explorer 10 will include a Flash component, on both x86/x64, and ARM. This will be usable in both the desktop front-end and the touch-friendly Metro one. Flash will work on any site in the desktop browser, and on a select set of whitelisted sites, including YouTube, Netflix, and CNN, in the Metro browser.

While the x86/x64 desktop browser will allow any plugins, the Metro browser will not; nor will either of the ARM browsers. This puts Flash in a very privileged position. Even Microsoft's own Flash-like Silverlight runtime isn't getting the same treatment.

Explaining the decision to incorporate Flash, Microsoft calls it a "practical matter," and that having more sites "just work" in the Metro browser is the most important concern: users shouldn't be forced to put down their tablets and use a PC just because they come across a site that uses Flash.

The Flash plugin-that-isn't-a-plugin is based on the regular, fully-featured desktop version of Flash, not Adobe's now-discontinued mobile effort. Microsoft and Adobe have worked together to improve the battery life and security of the Flash player, with Adobe supporting Windows platform features such as ASLR, and adopting and adapting Microsoft's Secure Development Lifecycle. Contrary to our previous report, however, Adobe says that it hasn't given Microsoft access to the source code; it merely hands over compiled binaries.

Being integrated into Internet Explorer, the Flash plugin will be updated by Microsoft, through Windows Update, just as is already done in Google Chrome. The whitelist, too, will be subject to periodic updates, so we might expect to see new sites added and others removed, according to user demand and migration to HTML5 technologies.

In practice, it works about as well as can be expected. It calls itself version 11.3 (compared to the current 11.2 for other platforms), and if you visit a whitelisted site, it fires up the Flash content without any fuss or indication that it's doing so.

Microsoft says that it has worked to make the Metro Flash (though not the desktop one) more amenable to touch content: it supports double-tap and pinch-to-zoom, for example, but doesn't support mouse hover effects. This may be true, but the broader problem—plenty of Flash content just isn't designed for touch—remains. YouTube, for example, all works, but certain features, such as the quality/resolution menu, are a little too dainty for convenient fingering.

In spite of concerns over security and battery life, having Flash is, at this stage in the Web's life, still better than not having Flash. One can, for example, just follow links to YouTube, without being taken out of the browser experience and into a separate YouTube application, and without having to worry about whether a given video supports HTML5 viewing (not all do). In a contradictory sense, the Metro browser manages to achieve a more Web-native experience (insofar as it doesn't depend on "there's an app for that," for rich content, letting you stay within the browser) by allowing the use of non-Web technology.

One major side-effect of the whitelisting is that online advertising, which isn't whitelisted (except for that integrated into sites like YouTube or Hulu) uses the non-Flash fallback. This will probably make advertisers unhappy, but not as much as Internet Explorer's other big change: it enables Do Not Track by default.

Rebuffing Advertisers

Do Not Track indicates to online advertisers and other stats gatherers that they wish to remain private. Every request sent to a Web server includes a header to show the user's explicit desire to remain private. Companies that honor this setting will accordingly have a greatly reduced ability to gather analytical data about those users.

Respecting the Do Not Track header is entirely optional at this point in time. A few high-profile sites have opted to honor it, most recently Twitter. Other major online players, including Google, have not. Microsoft says that enabling it is all part of the company's "private by default" commitment. It can be turned off if desired, but it will ship enabled.

The decision is a contentious one. Because Do Not Track is optional, it needs buy-in from advertisers and analytics firms. Those firms have been tentatively supporting Do Not Track, because it's currently positioned as an opt-in feature. The kinds of users who'd opt in are likely to be the same kinds of user who wouldn't click on advertisements anyway, so the inability to perform behavioral analysis of those users doesn't matter that much.

But as explored more fully by Ryan Singel over at Wired, there's a great concern that Microsoft's decision will derail the plans. With Internet Explorer 10's default, there's a prospect that before too long, 25 percent or more of Web users will have disabled tracking, and that changes the landscape considerably—enough that advertisers might not be willing to play ball.

New Specs

Do Not Track is just one of the many emerging standards that Internet Explorer 10 will support. When supporting features that are early in their development, new CSS and JavaScript features are given vendor-specific prefixes. For example, a CSS property transform is named -webkit-transform or -moz-transform or -ms-transform in the different implementations by WebKit (used in Chrome and Safari), Mozilla Firefox, or Internet Explorer, respectively. This allows the different vendors to safely implement different versions of the specification as it undergoes its development, so that they can learn more about the feature and how well it works.

Once the specifications reach a certain level of maturity, major changes to their syntax or functionality are ruled out, and the vendors start dropping the prefix, to allow the same, standard-targetting code to work cross-browser.

A number of preliminary specifications that Internet Explorer 10 implements have now reached that level of maturity, called "Candidate Recommendation," or are expected to do so shortly. As such, Microsoft has started supporting non-prefixed versions of a bunch of CSS and JavaScript features.

These include CSS transforms, animations, and gradients, which together allow Web pages to emulate the kind of effects that Microsoft's venerable WordArt feature made possible in the 1990s.

Internet Explorer 10 also includes a new feature to make touch navigation easier. An unfortunate reality of browsing the Web on touch devices is that many sites simply aren't designed for it. They include small links that are tightly packed together, forcing you to zoom in just to hit them. Particularly common culprits are the numbered links for paged articles, forum threads, and so on. Internet Explorer 10 has a neat new feature, Flip Ahead to take the pain out of such content.

Metro-style Internet Explorer uses a pair of gestures, swipe from left-to-right, and swipe from right-to-left to go back and forward, respectively. With Flip Ahead enabled (it's off by default), the right-to-left gesture changes meaning: it means "go to the next page of this multi-page article."

This is a neat little feature. I just hope Microsoft can figure out a way to include it that doesn't replace the normal "forward" browser behavior.

There's one more feature to Internet Explorer 10 that's palpable: it's fast. And it feels fast. Benchmarks may not show it, but Internet Explorer 10, even in a virtual machine, manages to feel smoother when scrolling and navigating than Chrome running on bare hardware.

Internet Explorer will ruffle a few feathers with the decisions Microsoft has made, but users may not care: it's shaping up to smart, effective browser that looks good, and works well. And it'll have a unique feature that no other tablet browser can offer: Flash that actually works.