private void QuanLyKhachHang_Click(object sender, RoutedEventArgs e)
{
QLKhachHang f = new QLKhachHang(TENDN);
f.Show();
this.Close();
}
private void btnDKKh_Click(object sender, RoutedEventArgs e)
{
QLKhachHang kh = new QLKhachHang(TENDN);
kh.ShowDialog();
}