function expand(num)
{
  element = document.getElementById("spam_item[" + num + "]");
  button = document.getElementById("button[" + num + "]");
  button_src_root = button.src.substring(0,button.src.lastIndexOf('/') + 1);
  if (element.style.display == "none")
  {
    element.style.display = "inline";
    button.src = button_src_root + "delete.png";
  }
  else
  {
    element.style.display = "none";
    button.src = button_src_root + "add.png";
  }
}