1. In a computer system comprising an input device, an apparatus for simulating input events from the input device as if the simulated input events are real input events generated by the input device, said apparatus comprising: (a) an interpreter responsive to commands of a first executing program of the computer system for generating simulated input device messages from the input device as if the simulated input device messages are real input device messages generated by the input device; and (b) a router cooperative with said interpreter and interposed between a window server of said computer system and said input device in an input/output stream of said computer system connecting said window server to said input device for routing upstream the generated simulated input device messages to said window server which in turn would translate the simulated input device messages into simulated input device events and continue to forward upstream the simulated input device events to a second executing program of said computer system, said router being also used to handle upstream routing to and downstream routing from said window server for non-simulated real input/output device messages being exchanged between said input device and executing programs of said computer system.