private void button_back_Click(object sender, RoutedEventArgs e)
        {
            Tworzenie_nowego_zlecenia new_order = new Tworzenie_nowego_zlecenia();

            this.Close();
            new_order.ShowDialog();
        }
        private void button_main_menu_create_new_order_Click(object sender, RoutedEventArgs e)
        {
            SaveFileDialog new_order_dialog = new SaveFileDialog();

            new_order_dialog.Title           = "Create new order"; //jezykowo to zrobic
            new_order_dialog.Filter          = "Order file|*.fro";
            new_order_dialog.OverwritePrompt = true;

            if (new_order_dialog.ShowDialog() == true)
            {
                //new_order_dialog.FileName = new_order_dialog.FileName.Substring(0, new_order_dialog.FileName.Length-4);
                System.IO.FileStream order_file = (System.IO.FileStream)new_order_dialog.OpenFile();

                //order_file.Close();

                //po pomyslnym ukonczeniu okna dialogowego
                Tworzenie_nowego_zlecenia new_order = new Tworzenie_nowego_zlecenia(System.IO.Path.GetFileName(order_file.Name));
                this.Close();
                new_order.ShowDialog();
            }
        }