1. A set of data processing systems operating utilizing a single set of input devices, comprising: a single set of input devices including a pointing device; at least two data processing systems sharing the single set of input devices, each data processing system having a logical display area logically arranged to have at least one boundary in common with a display area for another data processing system, wherein a pointer driven cursor controlled by the pointing device is located within a display area for an active data processing system receiving input signals from the single set of input devices; and switching means, responsive to movement of the cursor past a logical common boundary between two display areas, for automatically switching transmission of signals from the single set of input devices from the active data processing system to another data processing system corresponding to a display area sharing the logical common boundary with the display area for the active data processing system, wherein the other data processing system becomes the active data processing system.