Just found another quirk, that I want to keep under record in here :
Due to restrictions imposed by Windows 8 however, you will only be able to use one browser at a time in Metro mode. In Windows 8, only one browser will be allowed to run in Metro mode, and that is the browser you set as default. If your default browser is Internet Explorer, you will be able to use only Internet Explorer in Metro mode, all other browsers will open in “classic desktop” mode even if launched from Metro. This is rather annoying limitation since it is quite possible that some people will prefer, say Chrome as the default desktop browser, while Firefox or IE in Metro mode. As such, if you do want to try out this preview, you will need to make Firefox the default browser.
Read the rest at : http://www.devworx.in/features/firefox-metro-version-for-windows-8-now-available-for-preview-128741.html