[TIMOB-6208] Open NavigationGroup multiple times crashes the app

function NavGroup(){
	var w = Ti.UI.createWindow();
	var n = Ti.UI.iPhone.createNavigationGroup();
	var win = Ti.UI.createWindow({
		backgroundColor:'#444'
	});
	n.window = win;
	
	var close = Ti.UI.createButton({
		title:'back'
	});
	win.rightNavButton = close;
	
	close.addEventListener('click', function(){
		w.close();
	});

	w.add(n);
	return w;
}

function Window(){
	
	var win = Ti.UI.createWindow({backgrounColor:'green'});
	var btn = Ti.UI.createButton({
		width:100,
		height:40,
		title:'open'
	});
	win.add(btn);
	btn.addEventListener('click', function(){
		NavGroup().open();
	});
	
	return win;
}

Window().open();