// find all child of parent
        private void soLuongCom_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            //init_monandachon();
            double kaloFollow;
            ComboBox combo = sender as ComboBox;

            // cho lan chay dau tien, khi tag chua duoc binding
            if (combo.Tag == null) return;
            // lay tag của nhóm
            int checkTag = (int)combo.Tag;

            // lấy số lượng chọn
            int soluong = Int32.Parse((combo.SelectedItem as ComboBoxItem).Content.ToString());
            // thay doi phan tu o list
            ThucDon td = monanChonList.Find(r => r.IdMonAn == checkTag);
            if (td == null) td = new ThucDon();
            td.SoLuong = soluong;

            var lstText = AllChildren(combo.Parent).OfType<TextBlock>();
            // truong hop check box chua duoc check
            if (((combo.Parent as StackPanel).Parent as CheckBox).IsChecked == false)
            {
                foreach (var item in lstText)
                {
                    if ((item as TextBlock).Name.Equals("kaloBlock"))
                    {
                        // lay luong kalo cua mon an tu list;
                        double kaloBD = monAnList.Find(r => r.IdMonAn == checkTag).LuongKaloTrenDonVi;
                        // nhan voi so luong
                        kaloFollow = kaloBD * soluong;
                        // roi day ra man hinh
                        (item as TextBlock).Text = kaloFollow.ToString();

                    }
                }
            }
            // truong hop check box da duoc check
            else
            {
                foreach (var item in lstText)
                {
                    if ((item as TextBlock).Name.Equals("kaloBlock"))
                    {
                        // phai tru di luong ban dau
                        TongLuongKalo -= Double.Parse((item as TextBlock).Text);
                        // lay luong kalo cua mon an tu list;
                        double kaloBD = monAnList.Find(r => r.IdMonAn == checkTag).LuongKaloTrenDonVi;
                        // nhan voi so luong
                        kaloFollow = kaloBD * soluong;
                        td.LuongKalo = kaloFollow;
                        // cong lai luong thay doi
                        TongLuongKalo += kaloFollow;
                        // roi day ra man hinh
                        (item as TextBlock).Text = kaloFollow.ToString();

                    }
                }
            }
        }
        //chuyen trang sau dialog
        //public void chuyenPage(IUICommand command)
        //{
        //    //Frame.Navigate(typeof(KaloNgoaiPage));
        //}
        private void CheckBox_Checked(object sender, RoutedEventArgs e)
        {
            ThucDon td = new ThucDon();

            // them cac IdThongKeNgay o day
            td.IdThongKeNgay = thongkengay.IdThongKeNgay;
            var checkMonAn = sender as CheckBox;
            td.IdMonAn = (int)(checkMonAn.Content as StackPanel).Tag;

            td.SoLuong = Int32.Parse(((checkMonAn.Content as StackPanel).Children.OfType<ComboBox>().FirstOrDefault().SelectedItem as ComboBoxItem).Content.ToString());
            var listBlock = AllChildren(checkMonAn.Content as StackPanel).OfType<TextBlock>();
            foreach (var item in listBlock)
            {
                if ((item as TextBlock).Name.Equals("kaloBlock"))
                {
                    td.LuongKalo = double.Parse((item as TextBlock).Text);
                    TongLuongKalo += double.Parse((item as TextBlock).Text);

                }
            }
            // chua co idThongKeNgay
            monanChonList.Add(td);
        }