[TIMOB-7613] Custom barImage with Tab sub navigation displays previous barImage, not the current window barImage

// this sets the background color of the master UIView (when there are no windows/tab groups on it)
Titanium.UI.setBackgroundColor('#000');

// create tab group
var tabGroup = Titanium.UI.createTabGroup();


//
// create base UI tab and root window
//
var win1 = Titanium.UI.createWindow({  
    title:'Tab 1',
    backgroundColor:'#fff',
    barImage:'nav_bg.png',
    tabBarHidden:true
});

var button = Ti.UI.createButton({
	title:'open',
	width:100,
	height:50
});

button.addEventListener('click', function() {
	//win2.open();
	tabGroup.activeTab.open( win2 );
})

win1.add(button);

var win2 = Titanium.UI.createWindow({  
    title:'Tab 2',
    backgroundColor:'#fff',
    barImage:'nav_bg_2.png',
});

var tab1 = Titanium.UI.createTab({  
    title:'Tab 1',
    window:win1
});


tabGroup.addTab(tab1);  

// open tab group
tabGroup.open();