Ahead of the consumer launch of the upgraded mobile operating system, Microsoft has released the development kit for Windows Phone 7.8.
It's now available as an optional update that adds two new Windows Phone 7.8 emulator images to a user's existing SDK installation. "These two emulator images should enable you to fully test how your Windows Phone 7.5 app’s Live Tiles will look and behave when they are run on a device running Windows Phone 7.8. New phones with Windows Phone 7.8 are beginning to ship, so it’s a great time to update your apps to take advantage of the new Live Tile experience and to reach the new markets that Windows Phone 7.8 makes available."
"After you install the Windows Phone SDK update and fire up your app in one of the new Windows Phone 7.8 emulators, you’ll immediately be greeted by the familiar minimalistic UI experience (all you have is Internet Explorer on the start screen) and Windows Phone 7 device skin. And after pinning your app to the start screen, you’ll also notice that 7.8 now provides the option to make your app’s tile smaller. By default, the OS simply shows a smaller version of your standard app tile. To customize the appearance of your small tile, you’ll need to do some additional work."
Microsoft has yet to officially confirm when the Windows Phone 7.8 operating system will be made available to those with existing Windows Phones, but several carriers have mentioned a January 31 launch. The 7.8 operating system is already shipping on new Windows Phones.
As explained by Microsoft above, Windows Phone 7.8 will introduce the resizable tiles deriving from Windows Phone 8. A "new Start screen" will also be included, in addition to Xbox Music and SmartGlass.