private void AttachEvents()
        {
            if (_eventsAttached)
            {
                return;
            }

            var domWindow = Browser.GetContentDOMWindowAttribute();

            EventTarget = Xpcom.GetPrivateRoot((nsISupports)domWindow).AsComPtr();
            foreach (string sEventName in this.DefaultEvents)
            {
                using (var eventType = new nsAString(sEventName))
                    EventTarget.Instance.AddEventListener(eventType, this, true, true, 2);
            }

            _eventsAttached = true;
        }