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   string  $text       The text of button.
 * @param   bool    $newWindow  Whether to open the preview in _blank or just a modal
 *
 * @return  PopupButton|LinkButton
 *
 * @since   4.0.0
 */
public function preview(string $url, string $text = 'JGLOBAL_PREVIEW', $newWindow = false)
{
    if ($newWindow === true) {
        $button = $this->linkButton('link', $text)->url($url)->attributes(['target' => '_blank'])->icon('icon-eye');
    } else {
        $button = $this->popupButton('preview', $text)->url($url)->iframeWidth(640)->iframeHeight(480)->icon('icon-eye');
    }
    return $button;
}