text: UI.BackButton = function(win, cb) {
  	
  	var back = Ti.UI.createButton({
  		backgroundImage: "images/back_button.png",
  		top: 10,
  		right: 10,
  		width: 40,
  		height: 40
  	});
  	
  	back.addEventListener('click', function(){
  		win.close();
  		if(cb) cb();
  	});
  	
  	return back;
  }
  