Conventional graphical user interface systems are capable of rendering multiple application windows on a display space (e.g., a desktop) at a given time. A conventional graphical user interface system includes a compositor and one or more content buffers. The compositor maintains information about the visible regions of each window and its location on the display. A content buffer can be maintained for each window and include the content of the respective window. The compositor paints each window on the display according to the visible regions of each window and the underlying content maintained in the respective content buffers. When a region of the display requires updating (e.g., window movement, window resizing or content updating), the compositor assembles new content for the affected region by combining content from all the content buffers that contribute content to the region.
Compositors can be used to render the content for a variety of displays including various output display devices, display content recorders (e.g., screen capture) or other systems or components for various purposes (e.g., for the purposes of remote control by for example the Apple Remote Desktop).