It seems that Microsoft had to create a special category of applications to permit third party web browsers in its new Metro user interface. The new interface, much like Apple's iOS used on iPhones and iPads, places significant restrictions on what applications can do. But, unlike iOS, these restrictions apply to the new preferred interface for Microsoft's desktop operating system. And, that makes things a whole lot more complicated than they are with a phone and tablet OS.
I'm still uncertain about Windows 8's fusion of a desktop and tablet OS. This new complication just seems like another demonstration of the roadblocks Microsoft faces in making the next Windows a viable operating system.