var pop = null;

function popdown() {
  if (pop && !pop.closed) pop.close();
}
function win(obj,w,h) {
  var url = (obj.getAttribute) ? obj.getAttribute('href') : obj.href;
  if (!url) return true;
  w = (w) ? w += 00 : 150;  // 150px*150px is the default size
  h = (h) ? h += 00 : 150;
  
  var args = 'width='+w+',height='+h+',resizable, scrollbars=yes';
  popdown();
  pop = window.open(url,'',args);
  return (pop) ? false : true;
}