1. A computer implemented system for developing an application program having functionality that corresponds to a finite state machine (FSM) model, including: a visual interface that generates a graphical environment on a display, the graphic environment including a workspace for displaying an FSM model representing functionality of an application program, the FSM model including a plurality of elements including state elements and transition elements connecting the state elements; a dynamic state machine processor (DSMP) that uses the FSM model elements to generate the application program executed at run-time, each of the FSM elements including a markup language description defining the functionality of the element, at least some of the markup language descriptions including calls to standard actions corresponding to basic software functions; and an extensible graphic user interface (GUIX) that provides the end-user interface features to the end-user as generated during run-time by the DSMP based on the FSM model elements; wherein the visual interface includes a plurality of editor buttons, activation of which cause the visual interface to display editor windows that permit a technician to define or modify functionality of the FSM elements, the markup language descriptions of the functionality being stored in a database.