Two object-oriented models to design graphical user interfaces

Object-oriented concepts are well-suited to deal with the characteristics of user interfaces. Up to now several attempts to integrate the object-oriented paradigm in user interface models were envolved and led to destictive resulting models due to different requirements of the target application area. Within this paper two independently developed object-oriented interaction models are presented which emphasize the graphical requirements to user interfaces. These are among others its hierarchical nature, dynamical topology of the user interface, strong connection between input, output and the semantics of the application and the diversity of the graphics input devices and interaction techniques. Both approaches converge in the following aspects: Instead of having separated user interface layers the components of an interactive graphics application's user interface are embedded locally within interaction objects. Therefore dialogue control, input, output and the dynamical behaviour are o rganized as a micro-cosmos within each object. Compound interaction objects can be designed. Temporal logical operators are uesd to specify the dialogue. Tools to support the implementation of each model are described. By describing both approaches this paper could be a contribution toward establishing a uniform object-oriented framework for the design of graphical user interfaces