// window opener function
function popwin(URL, name, w, h)
{
   var winl = (screen.width - w) / 2;
   var wint = (screen.height - h) / 2;
	window.open(URL, name, "width="+w+", height="+h+", status=yes, scrollbars=yes, resizable=yes, menubar=no, toolbar=no, left="+winl+", top="+wint);
}