function change_image_to(this_obj, image_src) {
  if (this_obj['src']) {
    this_obj.src = image_src;
    return;
  }
  var children = this_obj.childNodes;
  for (var i = 0; i < children.length; i++) {
    if (children[i].nodeName == 'IMG') {
      children[i].src = image_src;
      return;
    }
  }
}