Windows Phone 8.1 may have only just reached the general public, but it's already in line for a surprisingly large update. Microsoft has posted developer documents (sign-in required) for Windows Phone 8.1 GDR1, a tweak that fills in a few key hardware and software gaps. Aside from previously revealed folder support, the upgrade will allow for smart cases akin to HTC's Dot View or LG's QuickCircle. Phone makers will get to run special apps when the cover is closed, and specify what happens when it's open. This seemingly simple addition could be important, since The Verge claims that HTC is preparing a Windows Phone version of the new One -- such a device would need smart cover features to perform the same tricks as its Android counterpart.