docs: public ScreenField getSField(int index)
      {       // If this screen cant accept a select BaseTable, find the one that can
          if ((index-DBConstants.MAIN_FIELD >= m_SFieldList.size()) || (index < Constants.MAIN_FIELD))
              return null;
          try   {
              return (ScreenField)m_SFieldList.elementAt(index-Constants.MAIN_FIELD);
          } catch (ArrayIndexOutOfBoundsException e)  {
          }
          return null;    // Not found
      }