Office AddIn - Communication with a window

Hi,

I am developing an Add In for Office 2013 Word and Excel with Javascript API.

I launch a window with window.open('url of window');

I want to communicate with this window.

Inside this there is 

window.addEventListener('message', function(event) {
alert(event.data);
}, false);

window.opener.postMessage('BACK_MESSAGE', '*');

And in my home js, there is also :

window.addEventListener('message', function(event) {
alert(event.data);
}, false);

But I don't receive any data from the window. I saw the wikipedia sample with iFrame communication adn sandbox, but I don't want to have a iFrame inside home.html.

So, how can we established the communication?

Thanks.