public static DialogResult ShowDialog(DateSettings dateSettings)
        {
            if (dateSettings == null)
            {
                throw new ArgumentNullException("dateSettings");
            }

            using (var form = new DateSettingsDialog(dateSettings.Copy()))
            {
                if (form.ShowDialog() == DialogResult.OK)
                {
                    dateSettings.Copy(form._dateSettings);
                }

                return(form.DialogResult);
            }
        }