how to do subwindow with nav using struct

foowin.js

/**
* Appcelerator Titanium Platform
* Copyright (c) 2009-2011 by Appcelerator, Inc. All Rights Reserved.
* Licensed under the terms of the Apache Public License
* Please see the LICENSE included with this distribution for details.
**/
// Code is stripped-down version of Tweetanium, to expose new structure paradigm

(function(){
	S.ui.createFooWin = function(){
		var win = Ti.UI.createWindow({backgroundColor: "red",title:"foo"});
		win.add(Ti.UI.createLabel(S.combine({text: "See blogpost @ http://blog.krawaller.se"},$$.Label)));
		var button = Titanium.UI.createButton({
		   title: 'Hello',
		   height: '20px'
		});
		button.addEventListener('click',function(e)
		{
		   subwin = S.ui.createsubwin();
		   subwin.open();
		});
		win.add(button);
		return win;
	};
	
	S.ui.createsubwin = function(){
		var win = Ti.UI.createWindow({backgroundColor: "red",title:"test sub"});
		win.add(Ti.UI.createLabel(S.combine({text: "Subwin test."},$$.Label)));
		return win;
	}
})();