iOS: Navgroup Closing window

app.js

var win = Titanium.UI.createWindow();

var win1 = Titanium.UI.createWindow({
    backgroundColor:"red",
    title:"Red Window"
});
win1.addEventListener('click', function(){
    nav.open(toolsWindow);
});

var nav = Titanium.UI.iPhone.createNavigationGroup({
   window: win1
});

var toolsWindow = Ti.UI.createWindow({
    title: 'Blue Window',
    url: 'tools_window.js',
    nav: nav,
    exitOnClose: false,
    backgroundColor: 'blue'
});

win.add(nav);
win.open();

tools_window.js

var win = Ti.UI.currentWindow;

var button = Ti.UI.createButton({
    title: 'close',
    height: 40,
    width: 300
});
button.addEventListener('click', function(e) {
    Ti.API.info('clicked close');
    win.nav.close(win);
});

win.add(button);