code: public int doRecordChange(Field field, int iChangeType, boolean bDisplayOption)
      {
          if (field != null)
              if (iChangeType == Constants.SCREEN_MOVE)
                  this.firePropertyChange(field.getFieldName(), null, field.getData());
          return Constants.NORMAL_RETURN;
      }
docs: Called each time a field changed.
  This method replaces behaviors in the thick model. Just override this method and look for the
  target field and do the listener associated with a change of value.
  Note: The thin version (this one) keeps a flag for changes, the thick version surveys the fields.
  @param field The field that changed.
  @param iChangeType The type of change (See record for the list).
  @param iDisplayOtion The display option.
  @return The error code.