Abstract: An event notification system for propagating object-change information. The notification system supports change notification without queues in an object-based application or operating system and can be scaled to propagate large numbers of events among a large plurality of objects. The event notification system interconnects a plurality of event source and event receiver objects. Any object, such as a command object, may operate as either an event receiver object, an event source object or both. A notification object is created by a source object to transport, from a source to a receiver, descriptive information about a change, which includes a particular receiver object method and a pointer to the source object that sent the notification. A receiver object must register with a connection object its “interest” in receiving notification of changes; specifying both the event type and the particular source object of interest.

Abstract: A method and apparatus for a menu based system containing size and location information is disclosed. Each menu contains a list of menu items containing a command and variables that reflect the command's current appearance. This includes status information determinative of the menu item's state (enabled/disabled), its name, its associated graphic, and whether its appearance is currently valid. Each of these were initialized when the menu item was created. The invention creates a menu item from a command, where a menu item is another object data structure containing a command sequence. The menu item is added to a list of menu items, and initialized as an invalid appearance. Later when the menu item is selected from a pull down menu, the appearance state is recomputed based on the system state.