function popup(w,h,url,n)
	{
	l = (screen.availWidth/2)-(w/2);
	t = (screen.availHeight/2)-(h/2);
	win = window.open(url,n,"width="+w+",height="+h+",left="+l+",top="+t+",resizeable=0,scrollbars=0,toolbar=0,status=0,directories=0,menubar=0,location=0");
	win.focus();
	}