Abstract: A reusable isolated undo/redo service provides application programs with an undo/redo function. Each application that will use the service is registered. Whenever a registered application performs an action that can be undone, it forms a packet and gives the packet to the service. Whenever the user of a registered application wishes to undo or redo an action, the undo or redo processing is performed by the service.

Abstract: A method and apparatus are disclosed for graphically accessing of multiple simultaneously active software applications within a data processing system having a video display screen having fixed dimensions. An electronic work space is established having dimensions substantially larger than the dimensions of the video display screen. Electronic representations of multiple software applications within viewports or "windows" are then disposed at selected locations within the electronic work space. A movable viewport, having effective dimensions substantially equal to the dimensions of the video display screen, is then utilized to permit the graphic presentation of selected software applications by selectively relocating the viewport within the electronic work space.