private void btnChonKhachHang_Click(object sender, RoutedEventArgs e)
        {
            UserControlLibrary.WindowTimKhachHang win = new UserControlLibrary.WindowTimKhachHang(mTransit);
            if (win.ShowDialog() == true)
            {
                mBOXuliTinhTien.BanHang.KhachHangID = win._KhachHang.KhachHang.KhachHangID;
                mBOBanHang.KHACHHANG = win._KhachHang.KhachHang;

                txtGiamGia.Text      = Utilities.NumberFormat.FormatToString(win._KhachHang.LoaiKhachHang.PhanTramGiamGia);
                txtGiamGia.IsEnabled = false;

                LoadKhachHang();
            }
        }
        private void btnChonKhachHang_Click(object sender, RoutedEventArgs e)
        {
            UserControlLibrary.WindowTimKhachHang win = new UserControlLibrary.WindowTimKhachHang(mTransit);
            if (win.ShowDialog() == true)
            {
                mBOXuliTinhTien.BanHang.KhachHangID = win._KhachHang.KhachHang.KhachHangID;
                mBOBanHang.KHACHHANG = win._KhachHang.KhachHang;
                
                txtGiamGia.Text = Utilities.NumberFormat.FormatToString(win._KhachHang.LoaiKhachHang.PhanTramGiamGia);
                txtGiamGia.IsEnabled = false;

                ReLoadData();
                LoadKhachHang();                
            }
        }