function showSpoiler(obj) 
{
  var inner = obj.parentNode.getElementsByTagName("div")[1]; 
  var img   = obj.getElementsByTagName("img")[0]; 
  if (inner.style.display == "none") 
  {
    img.src = "../../minus.png"; 
    inner.style.display = ""; 
  }
  else 
  {
    inner.style.display = "none"; 
    img.src = "../../plus.png"; 
  }

}