Abstract: A view system provides an extensible mechanism for associating a logical set of windows and manipulating them as a unit. For example, operations can be applied across address spaces to all the members of the group. A group is constructed by inserting a reference to each view in the group in a layer object. The layer object, in turn, can be inserted into a data hierarchy structure in a hierarchy object. The data hierarchy structure defines front to back display levels on a display and defines which windows overlap. Since all the members of the group are in the same layer object, they move to different levels as a group. Polymorphism and extensibility are provided via the object-oriented architecture of the operating system.