private void btnKhachHang_Click(object sender, RoutedEventArgs e)
 {
     if (ucKhachHang == null)
     {
         ucKhachHang = new UserControlLibrary.UCKhachHang(mTransit);
     }
     spNoiDung.Children.Clear();
     spNoiDung.Children.Add(ucKhachHang);
 }
 private void btnKhachHang_Click(object sender, RoutedEventArgs e)
 {
     if (ucKhachHang == null)
     {
         ucKhachHang = new UserControlLibrary.UCKhachHang(mTransit);
     }
     spNoiDung.Children.Clear();
     spNoiDung.Children.Add(ucKhachHang);
 }