Method preview

/**
 * Writes a preview button for a given option (opens a popup window).
 *
 * @param   string   $url            The name of the popup file (excluding the file extension)
 * @param   bool     $updateEditors  Unused
 * @param   string   $icon           The image to display.
 * @param   integer  $bodyHeight     The body height of the preview popup
 * @param   integer  $modalWidth     The modal width of the preview popup
 *
 * @return  void
 *
 * @since   1.5
 */
public static function preview($url = '', $updateEditors = false, $icon = 'preview', $bodyHeight = null, $modalWidth = null)
{
    $bar = Toolbar::getInstance('toolbar');
    // Add a preview button.
    $bar->appendButton('Popup', $icon, 'Preview', $url . '&task=preview', 640, 480, $bodyHeight, $modalWidth);
}