code: public void init(BaseField field, String targetFieldName, DateTimeField fldOtherDate)
      {
          m_fldOtherDate = fldOtherDate;
          super.init(field, targetFieldName, null);
      }
docs: Constructor.
  @param field The basefield owner of this listener (usually null and set on setOwner()).
  @param iTargetFieldSeq The date field sequence in this owner to use to calc the difference.
  @param fldOtherDate The other date field to use in calculating the date difference. If null, uses the current time.