Guidelines

• Derive your class from the TCommandOn<> template class.
• Declare and define streaming operators to handle persistent storage.

• To provide specific behavior, override the HandleUndo and HandleRedo methods inherited from TCommandOn<>.
• When you define the constructor for a command, remember that for some constructors you must specify whether a command is undoable or not when the command is defined.
• Use a kSerialUndo command type if you want to allow unlimited undos. kRandomAccessUndo allows non-sequential undos, and kCantUndo blocks the undo of earlier commands.