1. An object-oriented dialog system for use in a computer system having a memory means, model data stored in said memory means, a plurality of objects which utilize said model data, means for receiving user commands and a visual display, said dialog system generating on said visual display a dialog box display containing a control display which includes a display of said stored model data and which can be manipulated by a user to modify said stored model data, said dialog system comprising: (a) means responsive to a first user command for generating a control object, said control object having a method for generating said control display, a method for generating said model data display, a method for generating a modify command for modifying said model data and a method for generating a data change notification; (b) means for activating said dialog box display in response to a second user command; and (c) means responsive to a user manipulation of said control display for executing said modify command to modify said stored model data and said model data display; and (d) means responsive to a modification of said stored model data for executing said method for generating a data change notification, said data change notification thereupon being forwarded to said plurality of objects.