function popup(url,w,h) {
		var winl = (screen.width-w)/2;
		var wint = (screen.height-h)/2;
		if (winl < 0) winl = 0;
		if (wint < 0) wint = 0;
		
		var page = url;
		windowprops = "height="+h+",width="+w+",top="+ wint +",left="+ winl +",location=no,"
		+ "scrollbars=yes,menubars=no,toolbars=no,resizable=no,status=no";
		window.open(page, "Silksoundbooks", windowprops);
	}