A method for modifying a system-defined user interface control on a computing device is described. The method includes wrapping, on the computing device, a system-defined control within a programmer-defined control at run-time and modifying functionality of the system-defined control at run-time. Modifying functionality includes intercepting an initial message for a system-defined control, preventing the system-defined control from rendering and rendering a programmer-defined control in place of the system-defined control. Modifying functionality also includes intercepting a message for the system-defined control, determining whether the message requires modified functionality and providing modified functionality if the message requires modified functionality. Modifying functionality also includes sending the message to the system-defined control if the message does not require modified functionality and providing regular functionality if the message does not require modified functionality.