We previously heard that Mozilla was planning a Metro version of Firefox, and now developer Brian R. Bondy has announced that the company has begun work on it. While that's good for Firefox fans, the real news is that the program is going to belong to a new, third type of Windows 8 apps: "Metro style enabled desktop browsers." We're still trying to figure it all out (and we think Microsoft is too), but from what we understand, this new, third type is an exception to Microsoft's rules and lets traditional Windows web browsers participate in the Metro experience. The third category would co-exist alongside Windows 8's two current categories — one for apps in the traditional, Windows 7-like environment, and another for those that belong in Metro. Programs in the new category will be traditional desktop applications that are allowed to have live tiles on the new Start menu and will be compatible with Metro's app contracts and new snap features.

According to a Microsoft document that explains how to develop an application in the new style, a Metro style enabled desktop browser will be a single app that works in both the Windows and Metro environments. To date, two different Internet Explorer programs have existed on Windows 8: a Metro version and a traditional version, but it sounds like that will soon change. However, according to Microsoft, the Metro version of these apps will only function if the user sets the program as the default web browser. Microsoft says that the limitation is in place to create a consistent user experience — one Metro internet browser that opens all web links from Metro apps. Unlike the Metro apps we've seen so far, these new browsers will be distributed via traditional methods instead of the Windows Store.

The benefit for developers is that browsers that are built in the new app category will be able to use Win32 APIs that browsers need (like those for rendering HTML5 and performing multiple background processes) while fitting in with the Metro design philosophy. In theory, this should mean that such browsers will also be able to support Flash — something current Metro web browsers can't do. Microsoft is urging developers to include code in their software that will have the new browsers open in either Windows or Metro mode depending on what type of program you clicked a link from; so hopefully you won't have the jarring experience of opening a link in Outlook in Office 15 and then getting pushed out to a Metro web browser.

While the details aren't yet clear, it does sound like this new category of apps will make it easier for developers to create third-party web browsers that adhere to the Metro guidelines. If you're disappointed to hear that the new category is only available for web browsers, there is always hope that Microsoft might open it up to other apps down the road. We'll let you know when we learn more.

Thanks, Anonymous!