March 17, 2012, 7:18 AM — Mozilla has kick-started development of a Metro-style version of Firefox for Windows 8, Google has committed to doing the same and Opera Software said yesterday that it's looking into the matter.
Those three browser makers would be chasing Microsoft, which has a five-month head start, having already built several iterations of Internet Explorer 10 (IE10) that run on both the Windows 8 traditional desktop and in the operating system's new Metro touch-first user interface (UI).
Mozilla, which first said a month ago that it would build a "proof-of-concept" edition of Firefox for Windows 8's Metro UI, recently revealed more details of the project.
According to Firefox engineer Brian Bondy, Mozilla began actual development of a Windows 8 browser last week.
It turns out that Microsoft will allow hybrid desktop-Metro apps, but will limit that third category -- after classic x86/64 Windows programs and Metro-only applications -- to something the Redmond, Wash. giant dubbed "Metro style enabled desktop browsers."
"Firefox will fall into the third category, meaning you can run Firefox as a desktop application, and you can run it as a Metro application," said Bondy in a March 9 post to his personal blog.
Metro style enabled desktop browsers can run outside the normal Metro sandbox and have access to most classic Windows APIs (application programming interface), as well as the new WinRT API, the backbone of the Metro side of Windows 8 application development.
The category also gets an important pass from Microsoft: A Metro enabled desktop browser circumvents the Windows Store -- the Microsoft-curated distribution channel for all Metro apps -- and when installed on the Windows 8 classic desktop, simultaneously installs the Metro version.
The biggest caveat for a Metro enabled desktop browser is that only the default browser -- which is set by the user -- can run in the Metro UI.
Like Windows 7, Windows 8 will initially assign IE as the default browser.
Mozilla's work began months ago, after last September's Build conference where Microsoft released the rough-edged Windows 8 Developer Preview. But programming was impossible until Microsoft provided documentation that described how to construct a crossbreed browser.