Systems and methods are provides for changing a user interface for a multi-screen device. The user interface can change based on the movement of a window. The system can receive a user interface event that modifies the display of windows in the user interface. Upon receiving the user interface event, the system determines if a window has been covered or uncovered. If a window has been covered, the window is placed in a sleep state. If a window is uncovered, the window is activated from a sleep state. A sleep state is a window state where an application associated with the window does not receive user interface inputs and/or does not render the window.