[TIMOB-11517] Android: On clicking the back button of device on third window, application closes instead of going to the previous window

Titanium.UI.setBackgroundColor('#000');

gt = { ui:{} };

gt.ui.createNavigationGroup = function(options) 
{
	var navGroup = 
	{
    	stack: [],
        window: options.window,
        to_root:options.to_root || false
    };

    navGroup.open = function(win, options) 
    {
        Ti.API.info('pre open stack length: ' + navGroup.stack.length);
        
        if (navGroup.stack.length == 0) 
        {
            navGroup.window.addEventListener('android:back', navGroup.go_back);
            Ti.API.info('addEventListener android:back');
        }

        navGroup.stack.push(win);
        win.open(options);
        Ti.API.info('after open stack length: ' + navGroup.stack.length);
    };

    navGroup.close = function(win, options) 
    {
        var idx = navGroup.stack.indexOf(win);
        Ti.API.info('idx: ' + idx);
        if (idx != -1) navGroup.stack.splice(idx, 1);
        win.close(options);
        win = null;
    };

    navGroup.go_back = function(options) 
    {
        var win = navGroup.stack.pop();
        if (win) 
        {
            win.close(options);
            win = null;
        }

        if (navGroup.stack.length == 0) 
        {
            Ti.API.info('removeEventListener android:back');
            navGroup.window.removeEventListener('android:back', navGroup.go_back);
            Ti.API.info('navGroup window close');   
        }

    };

    navGroup.go_home = function() 
    {
        while (navGroup.stack.length) 
        {
            navGroup.go_back();
        }
    };

    return navGroup;

}

var tabGroup = Titanium.UI.createTabGroup();

var navWindow = Ti.UI.createWindow(
{
    backgroundColor:'#ccc',
    navBarHidden:false
});


var tabWindow = Ti.UI.createWindow(
{
    backgroundColor:'#ccc'
});

tabWindow.addEventListener('click', function()
{
    navTab.open(navWindow);
});


var navBtn = Ti.UI.createButton(
{
    title:'open red win',
    color:'#f00',
    width:200,
    height:40
});

navWindow.add(navBtn);


var nav = gt.ui.createNavigationGroup(
{
    window:navWindow
});


navBtn.addEventListener('click', function()
{
    var win = Ti.UI.createWindow(
    {
        backgroundColor:'#fcc'
    });


    var navBtn2 = Ti.UI.createButton(
    {
        title:'open yellow win',
        color:'#ff0',
        width:200,
        height:40
    });


    win.add(navBtn2);

    navBtn2.addEventListener('click', function()
    {
        var win2 = Ti.UI.createWindow(
        {
            backgroundColor:'#ffc'
        });


        var navBtn3 = Ti.UI.createButton(
        {
            title:'close red win',
            color:'#000',
            width:200,
            height:40,
            top:50
        });


        navBtn3.addEventListener('click', function()
        {
            nav.close(win);
        });

        win2.add(navBtn3);


        var navBtn4 = Ti.UI.createButton(
        {
            title:'go home',
            color:'#0f0',
            width:200,
            height:40,
            top:150
        });


        navBtn4.addEventListener('click', function()
        {
            nav.go_home(win);
        });

        win2.add(navBtn4);

        nav.open(win2);
    })


    nav.open(win);
})


var navTab = Ti.UI.createTab(
{
  id: 'navTab',
  title:'navGroup',
  window:navWindow
});

tabGroup.addTab(navTab);

tabGroup.open();