private void btnAddExchanges_Click(object sender, EventArgs e)
        {
            ExchangesManager form = new ExchangesManager(null);

            if (form.ShowDialog() != DialogResult.OK)
            {
                return;
            }
            else
            {
                InitExchangesList();
            }
        }
        private void btnEditExchange_Click(object sender, EventArgs e)
        {
            SanGiaoDich      exch = cbbSanNiemYet.SelectedItem as SanGiaoDich;
            ExchangesManager form = new ExchangesManager(exch);

            if (form.ShowDialog() != DialogResult.OK)
            {
                return;
            }
            else
            {
                InitExchangesList();
            }
        }