//IMAGE

        // ADD

        private void AddImage_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                this.downSender      = sender;
                this.downTime        = DateTime.Now;
                BuyButton.Visibility = Visibility.Hidden;
                AdditionWindow addition = new AdditionWindow();
                addition.ShowDialog();
                bool?result = addition.DialogResult;
                if (result == true)
                {
                    items.Add(addition.GetAdditionItem());
                }
                if (mainlistbox.SelectedIndex > -1)
                {
                    BuyButton.Visibility = Visibility.Visible;
                }
            }
        }
        private void AddImage_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Released && sender == this.downSender)
            {
                TimeSpan timeSinceDown = DateTime.Now - this.downTime;
                if (timeSinceDown.TotalMilliseconds < 500)
                {
                    BuyButton.Visibility = Visibility.Hidden;
                    AdditionWindow addition = new AdditionWindow();
                    addition.ShowDialog();
                    bool?result = addition.DialogResult;
                    if (result == true)
                    {
                        items.Add(addition.GetAdditionItem());
                    }

                    if (mainlistbox.SelectedIndex > -1)
                    {
                        BuyButton.Visibility = Visibility.Visible;
                    }
                }
            }
        }