Mozilla will build a "proof-of-concept" version of Firefox for the Windows 8 Metro touch-first interface next quarter, then follow that with more functional editions later in the year.
The company is the first of Microsoft's browser rivals to publicly commit to a Metro edition. Microsoft has said it will ship both Metro and traditional desktop versions of Internet Explorer 10 (IE10) with Windows 8 and Windows on ARM (WOA), the new OS targeting tablets and other low-powered devices.
Metro is Microsoft's label for the touch-enabled interface at the centre of both Windows 8 and WOA. Windows 8 will run Metro and traditional 32-bit and 64-bit Windows applications, but WOA will run only those third-party apps designed for Metro.
In an update to its 2012 roadmap published at the weekend, Mozilla said that it would craft a "technology proof of concept" of Firefox on Metro as a first step. "This is not an alpha or a beta, but should demonstrate the feasibility of Firefox in Windows 8 Metro," explained Asa Dotzler, the product director of Firefox.
The proof of concept is currently slated to roll out in the second quarter of 2012. Alpha and beta versions of the browser will follow in July through December.
"The Alpha will prove the installation path and basic browsing features, and the beta will be feature complete for a 1.0-capability product," Dotzler added.
In a more detailed planning document, Mozilla spelled out some specific goals of Firefox on Metro, saying that it will rely on existing Gecko libraries in 32-bit Windows to avoid having to port the bulk of the browser's code to the WinRT API (application programming interface).
Gecko is the Firefox browser engine, while WinRT refers to "Windows Runtime," the new programming model Microsoft is promoting for developing Metro apps in Windows 8.
"Firefox on Metro will be a full-screen App with an Appbar that contains common navigation controls (back, reload, etc.,) the Awesomebar, and some form of tabs," the document said.
If Mozilla's assumptions are correct - that it will power Firefox Metro on Windows 8 via current Gecko libraries - its new browser would run only on Windows 8, not on WOA.
Mozilla has already put considerable resources into Firefox for Android, and has talked about creating a web-based operating system of its own, dubbed "Boot to Gecko," for tablets and smartphones.
Mozilla said it will have a better idea of the work necessary to create a Metro Firefox on Windows 8 after Microsoft ships the Consumer Preview of the new operating system on February 29.
Metro apps will be distributed only through the Windows Store, Microsoft has said.