/**
  * @see Page::show()
  */
 public function show()
 {
     parent::show();
     if ($this->action == 'newCaptchaID') {
         // get new captcha id
         $captchaID = Captcha::create();
         // send header
         header('Content-type: text/xml');
         HeaderUtil::sendNoCacheHeaders();
         // print xml
         echo "<?xml version=\"1.0\" encoding=\"" . CHARSET . "\"?>\n<captchaid>" . $captchaID . "</captchaid>";
         exit;
     } else {
         // send header
         header("Content-type: image/png");
         // show image
         $image = new CaptchaImage($this->captcha->captchaString);
     }
 }