WHAT’S NEW IN WINDOWS 8.1
Windows 8.1 introduces two new tile sizes (70×70 pixels and 310×310 pixels), and the four sizes now available are referred to as “small,” “medium,” “wide,” and “large” (instead of just “square” and “wide”). In order to take advantage of the new tiles sizes, you must specify images for them in the app manifest (package.appxmanifest), as they are not provided with the default templates.
The permissions on toast notifications have also been changed in Windows 8.1. As a developer, you have to specify if your app is toast capable or not.
In addition, the Windows Azure Mobile Services SDK is now implemented ...