In order to provide an alternative to IE on Windows 8, Firefox needs a Metro UI. Luckily, development of a Metro interface for Firefox is well underway. The current build reuses the Android interface XUL (by virtue of being based on Fennec). The latest test release features lots of platform integration support: "We have Metro snap working, you can snap another Metro app to the right or left of Firefox and continue browsing. We also have HTML file input controls tied up to the Metro file picker. ... implemented the Windows 8 search contract, you can use the Search Charm from any screen on Windows 8. If you enter a URL, it will be loaded. If you enter anything else, it will be searched in your default search engine. We also implemented the Windows 8 share contract, you can use the Share Charm from any Firefox page to share that page to another application. Once you select the Share Charm it will list the applications you can share to, for example: Mail, Twitter, or Facebook." If you're interested in following development, the team has made a Mercurial repository available.Further background is provided by the first and second posts in the series.