er handle</li>
    <li><b>NeedleMeter</b>, a curved scale with a straight needle indicator</li>
    <li><b>CircularMeter</b>, a circular scale with a polygonal needle indicator</li>
    <li><b>BarMeter</b>, a circular scale with an annular bar indicator</li>
  </ul>
  <p>
    The value to be shown by the instrument is assumed to be the <code>data.value</code> property.
    The value is shown both textually in a TextBlock and graphically using an indicator on the
    scale. If the value of <code>data.editabl