Mozilla started the development of the Firefox for Metro in late 2012. Since then, the team built and tested the product, but according to Nightingale, Metro's adoption remains pretty flat.
"On any given day we have, for instance, millions of people testing pre-release versions of Firefox desktop, but we've never seen more than 1000 active daily users in the Metro environment," he said.
The truth is that there is a low usage rate as few touch-enabled devices are running Windows 8. Every x86-based PC that runs any version of Windows, can run the desktop version of Firefox.
Microsoft is about to ship a major update to Internet Explorer next month with Windows 8.1 Update 1.