var pop = null;

function popdown() {
  if (pop && !pop.closed) pop.close();
}
function popup(aktu,w,h) {
  var url = (aktu.getAttribute) ? aktu.getAttribute('href') : aktu.href;
  if (!url) return true;
 	 w= (w) ? w += 30 : 155; 
 	 h= (h) ? h += 35 : 155;
  var args = 'width='+w+',height='+h+',resizable';
  popdown();
  pop = window.open(url,'',args);
  return (pop) ? false : true;
}

window.onunload = popdown;
window.onfocus = popdown;