gistfile1.js

Notifier.prototype.fire = function () {
    // first arg to delegate notifier should be an object with currentTarget
    var args     = toArray(arguments, 0, true),
        handle   = this.handle,
        ce       = handle.evt,
        sub      = handle.sub,
        thisObj  = sub.context,
        delegate = sub.filter,
        event    = e || {},
        ret;

    if (this.emitFacade) {
        if (!e || !e.preventDefault) {
            event = ce._getFacade();

            if (isObject(e) && !e.preventDefault) {
                Y.mix(event, e, true);
                args[0] = event;
            } else {
                args.unshift(event);
            }
        }

        event.type    = ce.type;
        event.details = args.slice();

        if (delegate) {
            event.container = ce.host;
        }
    } else if (delegate && isObject(e) && e.currentTarget) {
        args.shift();
    }

    sub.context = thisObj || event.currentTarget || ce.host;
    ret = ce.fire.apply(ce, args);

    // have to handle preventedFn and stoppedFn manually because
    // Notifier CustomEvents are forced to emitFacade=false
    if (e.prevented && ce.preventedFn) {
        ce.preventedFn.apply(ce, args);
    }

    if (e.stopped && ce.stoppedFn) {
        ce.stoppedFn.apply(ce, args);
    }

    sub.context = thisObj; // reset for future firing

    // to capture callbacks that return false to stopPropagation.
    // Useful for delegate implementations
    return ret;
};

gistfile2.js

Y.Event.define('tap', {
    publishConfig: {
        preventedFn: function (e) {
            // This should be moved to a prototype
            e.target.once('click', function (click) {
                click.preventDefault();
            });
        }
    },
    ...
});