$('#myIframe input').addEvent('focus', function() {
    // Do something
});

$('myIframe').contentDocument.getElements('input').addEvent(

$('myIframe').contentDocument.querySelector('input').addEventListener(

var iframe = new IFrame({
    src: '/RN95f/3/show',
    styles: {
        border: '2px solid #ccf'
    },
    events: {
        load: function () {
            alert('The iframe has finished loading.');
            this.contentDocument.getElements('input').addEvent('focus', function () {
                // Do something
                alert('focus on input detected!');
                console.log(this);
            });
        }
    }
});
$(document.body).adopt(iframe);

$('myIframe').onload = function() {
    $('myIframe').contentDocument.getElements('input').addEvent('focus', function() {
        // Do something
    });
};