function addEvent(obj, evType, fn){ 
  if (obj.addEventListener){ 
    obj.addEventListener(evType, fn, false); 
    return true; 
  } else if (obj.attachEvent){ 
    var r = obj.attachEvent("on"+evType, fn); 
    return r; 
  } else { 
    return false; 
  } 
}

function setOpacity(el, opac) {
  if (opac == null) opac = 95;
  el.style.filter = "alpha(opacity:" + opac + ")";
  el.style.KHTMLOpacity =  opac / 100;
  el.style.MozOpacity = opac / 100;
  el.style.opacity = opac / 100;
}

function getElementsByClass(searchClass,node,tag) {
  var classElements = new Array();
  if ( node == null )
    node = document;
  if ( tag == null )
    tag = '*';
  var els = node.getElementsByTagName(tag);
  var elsLen = els.length;
  var pattern = new RegExp("(^|\\\\s)"+searchClass+"(\\\\s|$)");
  for (i = 0, j = 0; i < elsLen; i++) {
    if ( pattern.test(els[i].className) ) {
      classElements[j] = els[i];
      j++;
    }
  }
  return classElements;
}