// Add Product Button Click event.
        private void AddProductButton_Click(object sender, EventArgs e)
        {
            this.Hide();
            indexOfSelectedPart = -1;
            dataGridViewProducts.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
            ProductScreen addProductScreen = new ProductScreen();

            // Change addModifyProductLabel Text to Add Product.
            addProductScreen.addModifyProductLabel.Text = "Add Product";
            addProductScreen.productIDTextBox.Text      = Inventory.CurrentProduct.ProductIDCount.ToString();

            // Change text colors to silver.
            addProductScreen.productNameTextBox.ForeColor = Color.Silver;
            addProductScreen.inventoryTextBox.ForeColor   = Color.Silver;
            addProductScreen.priceCostTextBox.ForeColor   = Color.Silver;
            addProductScreen.maxTextBox.ForeColor         = Color.Silver;
            addProductScreen.minTextBox.ForeColor         = Color.Silver;
            addProductScreen.ShowDialog();
        }
        private void ModifyProductsButton_Click(object sender, EventArgs e)
        {
            // Modify Existing Product.
            if (indexOfSelectedProduct >= 0)
            {
                this.Hide();
                ProductScreen modifyProductScreen = new ProductScreen();

                // Change addModifyProductLabel Text to Modify Product.
                modifyProductScreen.addModifyProductLabel.Text = "Modify Product";
                modifyProductScreen.productNameTextBox.Text    = Inventory.CurrentProduct.ProductName;
                modifyProductScreen.inventoryTextBox.Text      = Inventory.CurrentProduct.InStock.ToString();
                modifyProductScreen.priceCostTextBox.Text      = Inventory.CurrentProduct.ProductPrice.ToString();
                modifyProductScreen.maxTextBox.Text            = Inventory.CurrentProduct.Max.ToString();
                modifyProductScreen.minTextBox.Text            = Inventory.CurrentProduct.Min.ToString();
                modifyProductScreen.Show();
            }
            // Select a product to Modify.
            else
            {
                MessageBox.Show("Select a Product to modify!");
            }
        }