I'm loading an external script (that creates a new window component) into a panel, which works fine.

Now, I want to access the created window from a callback function to register a closed event handler. I've tried the following:

panel.load({
    scripts: true,
    url: '/createWindow',
    callback: function(el, success, response, options) {
        panel.findByType("window")[0].on("close", function { alert("Closed"); });
    }
});

However, the panel seems to be empty all the time, the findByType method keeps returning an empty collection. I've tried adding events handlers for events like added to the panel but none of them got fired.

So the question is: how do I access the window in the panel to register my close event handler on it?