At the 2014 Build conference, during April, Microsoft's Terry Myerson unveiled further user interface changes for Windows 8.1, including the ability to run Metro-style apps inside desktop windows, and a revised Start menu, which creates a compromise between the Start menu design used by Windows 7 and the Start screen, by combining the application listing in the first column with a second that can be used to display app tiles. Myerson stated that these changes would occur in a future update, but did not elaborate further. Microsoft also unveiled a concept known as "Universal Windows apps", in which a Windows Runtime app can be ported to Windows Phone 8.1 and Xbox One while sharing a common codebase. While it does not entirely unify Windows' app ecosystem with that of Windows Phone, it will allow developers to synchronize data between versions of their app on each platform, and bundle access to Windows, Windows Phone, and Xbox One versions of an app in a single purchase

