nly applicable when option <code>selectable</code> and <code>multiselect</code> are <code>true</code>.
      </td>
    </tr>

    <tr>
      <td>onAdd</td>
      <td>function</td>
      <td>none</td>
      <td>Callback function triggered when an item is about to be added: when the user double taps an empty space in the Timeline. See section <a href="#Editing_Items">Editing Items</a> for more information. Only applicable when both options <code>selectable</code> and <code>editable.add</code> are set <code>tr