There are many ways to support operations for an object, including direct manipulation of the object or its control point (handle), menu commands, buttons, dialog boxes, tools, or programming. Support for a particular technique is not exclusive to other techniques. For example, the user can size a window by using the Size menu command and by dragging its border.
Design operations or commands to be contextual, or related to, the selected object to which they apply. That is, determine which commands or properties, or other aspects of an object, are made accessible by the characteristics of the object and its context (relationships). Often the context of an object may add to or suppress the traits of the object. For example, the menu for an object may include commands defined by the object's type and commands supplied by the object's current container.