public VistaFileDialogEvents(VistaFileDialog dialog)
        {
            if( dialog == null )
                throw new ArgumentNullException("dialog");

            _dialog = dialog;
        }
        public VistaFileDialogEvents(VistaFileDialog dialog)
        {
            if (dialog == null)
            {
                throw new ArgumentNullException("dialog");
            }

            _dialog = dialog;
        }