     <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">

<p>Define a picking region. </p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">center</td><td>Specify the center of a picking region in window coordinates. </td></tr>
    <tr><td class="paramname">delta</td><td>Specify the width and height, respectively, of the picking region in window coordinates. </td></tr>
    <tr><td class="paramname">viewpo