Appcelerator Titanium Mobile - Custom events

app.js

var win1 = Titanium.UI.createWindow({  
    title:'Window 1',
    backgroundColor:'#fff'
});

var label1 = Titanium.UI.createLabel({
	color:'#999',
	text:'Window 1\nClick anywhere for opening Window 2',
	textAlign:'center',
	width:'auto'
});

win1.add(label1);

win1.addEventListener('click', function(e)
{
	var win2 = Ti.UI.createWindow({title: 'win2', url: 'win2.js'});
	win2.open();
});

Ti.App.addEventListener('myEvent', function(e)
{
	Ti.API.info('my event fired!');
	Ti.API.info('Custom data sent with the event: ' + e.customData);
	label1.text = 'I know you came from Window 2\ncustomData=' + e.customData;
});

win1.open();

win2.js

var win2 = Ti.UI.currentWindow;
win2.backgroundColor = 'black';
	
var label = Titanium.UI.createLabel({
	color:'#999',
	text:'I am Window 2\nclick anywhere for closing me',
	textAlign:'center',
	width:'auto'
});

win2.add(label);

win2.addEventListener('click', function(e)
{
	var evt = {customData: 'myData'};
	Ti.App.fireEvent('myEvent', evt);
	win2.close();
});

That's actually a really clear explanation. Thanks!