popwindow = 0;
function popup(url,w,h) {
	if ( popwindow != 0 ) popwindow.close();
  popwindow = window.open(url, "", "width="+w+",height="+h+",top=0,left=0,scrollbars=no,directories=no,location=no,menubar=no,resizeable=no,status=no,toolbar=no");
  return false;
}