// Construct with an item.
        public ItemDisplayBox(Item itemInTransaction, Transaction transaction, RemoveItemFromDisplay removeFunction, UpdateItemDisplay updateFunction, AddDiscountToDisplay addDiscountFunction, Employee currentUser)
        {
            InitializeComponent();

            SourceItem = itemInTransaction;
            m_transaction = transaction;
            m_removeFunction = removeFunction;
            m_updateFunction = updateFunction;
            m_addDiscountFunction = addDiscountFunction;
            m_currentUser = currentUser;
            NameField.Text = itemInTransaction.ItemName.Substring(0, Math.Min(itemInTransaction.ItemName.Length, 40));

            AmountField.Text = SourceItem.OriginalPrice.ToString( "C" );

            PreviewMouseLeftButtonDown += DisplayItemClickedEvent;
        }
        public DiscountDisplayBox(IDiscount discount, Item possesingItem,Transaction transaction, RemoveDiscountFromDisplay removeFunction, UpdateItemDisplay updateFunction, Employee currentUser)
        {
            InitializeComponent();

            SourceDiscount = discount;
            PossessingItem = possesingItem;
            m_transaction = transaction;
            m_removeFunction = removeFunction;
            m_updateFunction = updateFunction;
            m_currentUser = currentUser;

            NameField.Text = discount.ToString().Substring(0, Math.Min(discount.ToString().Length, 40));

            UpdateDiscountString();

            AmountField.Text = Discount;

            PreviewMouseLeftButtonDown += DisplayItemClickedEvent;
        }