var win = '';

function popup(url, width, height) {
   
   if (! win.closed && win.location) {
      // win.location.href = url;
   }
   else {
      win = window.open(url, 'popup', 'height=' + height + ',width=' + width + ',titlebar=no,menubar=no,location=no,toolbar=no,status=yes,scrollbars=yes,resizable=yes');
      if (! win.opener) {
         win.opener = self;
      }
   } 

   if (window.focus) {
      win.focus();
   }
         
   return false;
}

// $(window).unload(function() { alert("Bye now!"); });