1. For use in a computer system adapted to provide an object-oriented graphical user interface (GUI) for an application, said application GUI using one or more application model objects for modeling information and a mechanism to render and manipulate the application model objects, a method for integrating to said application GUI a command shell of a program for executing commands and providing text-based output generated in response to the executing, said method comprising: defining a command shell GUI model comprising command shell model objects for modeling information in said command shell, said command shell model objects comprising at least one of the application model objects; mapping text-based output of said command shell generated in response to a command to instances of said command shell model objects; and rendering and manipulating the instances of the command shell model objects, any instances of said application model objects being rendered and manipulated in accordance with the application GUI.