This thesis describes a framework for shared window systems with which a programmer can develop a multiuser interfaces for a computer-supported conferencing environment. Traditionally, computer users have used the computer as a tool for their decision making process. As much of the decision making process is done in work groups, sometimes in geographically distributed areas, the computer-supported conferencing becomes an important issue. There have been several attempts to implement the shared window system to develop the conferencing system. However, they don't provide enough functionalities in the floor control and the selective sharing, which are essential to reflect the dynamic change of the floor control and the coexistence of private and public space in a computer-supported conference. In this thesis, we propose a model of shared window systems based on group management. We solve the dynamic floor control by introducing "display object" and the selective sharing by selective use of the replicate transparency provided by the group management system. In addition, this approach reduces the complexity of programming and supports both replicated and centralized a chitecture in multiuser application.
