Abstract: A method, apparatus and system for allowing an end-user to define at run-time the way an object in the system will react to existing operations, or events, that are later performed on the object. In the system of the invention, the end-user can attach to the object code specifying behavior that the user wishes the object to exhibit from that point forward. The code defining the new or additional behavioral features will be interpreted by the applications software so that each time an event or operation is performed on the object, the system will recognize that the object has user-specified behavior associated therewith. The code remains associated with the object. In the system of the invention, there is no need to exit the application software. The new code specifying the desired behavior is immediately callable and executable by the system upon being input.