function setOp(which, opaque){
  var cl = 'opacity' + (opaque ? 2 : 1);
  if(document.getElementById){
    var el = document.getElementById(which);
    if(el){
      el.setAttribute('class', cl);
      el.setAttribute('className', cl);
    }
  } else {
    if(document[which]){
      document[which].className = cl;
    }
  }
}