-- Command: knob ID/K, COMMAND/K, PORT/K, HELP/K, NODE/K, ATTRS/K/M
     Knob gadget objects are created with this command.  Slider,
     popslider and knob gadgets are essentially identical with the only
     difference being the base object class to create each type of
     object.  All options are identical for these objects.  Refer to
     the slider command for descriptions of the options.