On other mobile platforms, the app can opt in for rotation/resize of its top-level windows when the device is rotated. However, Windows Phone does not do this (Windows 8/RT tablets do if this has been enabled in the settings, however) because native apps are responsible for doing this themselves.

It would be nice if the platform plugin had a way to do this transparently, so the developer wouldn't have to implement it on an app-by-app basis. It would require reporting transposed screen geometry, resizing the backing store, and remapping the input coordinates to transformed space.