the shape under the mouse should auto-highlight</p></td>
    </tr>
    <tr>
      <th>highlight_colour</th>
      <td><p>hex string colour to use for highlighting. Must contain the alpha component.</p></td>
    </tr>
    <tr>
      <th>legend</th>
      <td><p>either a logical indiciating if the legend(s) should be displayed, or
a named list indicating which colour attributes should be included in the legend.</p></td>
    </tr>
    <tr>
      <th>legend_options</th>
      <td><p>A list of options for contro