function pop(url, winname, x, y)
{
   var wp = "resizable=yes,width=" + x + ",height=" + y;

   if (typeof(z) == "undefined" || z.closed)
   {
		if (winname == "new")
		{
			wp = wp + ",scrollbars=yes";
			window.open(url, "_new", wp);
			return;
		}
		else if (winname == "")
         winname = "docwin";
      z = window.open(url, winname, wp);
   }
   else {
      z.close();
      pop(url, winname, x, y);
   }
}