QUESTION
 There are unlisted actions for both an okay and cancel pushbutton
 on a part's custom settings view, but how do you handle an apply
 pushbutton ?

ANSWER
 If you are creating a VisualAge part, and want the custom settings view
 to have an apply pushbutton, add an event-to-script connection from
 the pushbutton clicked event to the following script:

 *******For VisualAge version 1.0********

 apply

  | op newOp |

  op := (self partAttributeValue: #(#updateOperation #self)) execute.
  newOp := op target customSettingsOperation
   stackHolder: op stackHolder;
    defaultValuesSource: op defaultValuesSource;
    target: op target.
   self partAttributeValue: #(#updateOperation #self) put: newOp.

 *******For VisualAge version 2.0*******

 apply

   | op newOp |

   op := ((self subpartNamed: 'updateOperation') value) execute.
   newOp := op target customSettingsOperation
    stackHolder: op stackHolder;
    defaultValuesSource: op defaultValuesSource;
    target: op target.
 (self subpartNamed: 'updateOperation') value: newOp.