function add_comment() {

  $('commentform').style.display='block';
  if ($('captcha_img')) {
      var ver_key = $('ver_key').value;
      $('captcha_img').src = 'action.php?action=plugin&name=Captcha&type=captcha&key=' + ver_key;

  }
  var ele = $('add_comment');
  ele.removeChild(ele.childNodes[1]);
}

function $(id) {
  return document.getElementById(id);	
}