var fenster = null;

function popupWindow(url) {


	if (fenster) {
  		fenster.close();
  	}	 
  	fenster = window.open(url,'popupWindow','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=no,copyhistory=no,width=516,height=700,screenX=100,screenY=0,top=0,left=100');
}