Make DisplayList::Recorder override GraphicsContext::drawControlPart(). Create a new DisplayList item named DrawControlPart and new RemoteDisplayListRecorder message named DrawControlPart. Handle the encoding and decoding of the super classes of ControlPart. Because GPUP can render ControlParts simultaneously in multiple threads, we need to create a ControlPartFactory for every RemoteDisplayListRecorder which handles drawing the DisplayList item DrawControlPart.