1. A method of modifying a window stack in response to an orientation change of a multi-screen device, the method comprising: determining that the multi-screen device has rotated from a first orientation to a second orientation; determining a relative size and orientation of at least one window in a window stack stored on the multi-screen device based on the rotation of the multi-screen device; and controlling the display of the at least one window stored in the window stack based on the determined relative size and orientation of the at least one window in the window stack.