/// <summary>
        /// Edit a product group
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnChange_Click(object sender, RoutedEventArgs e)
        {
            // Make sure the sure the user has selected an item in the listview
            if (lvProductGroups.SelectedItem == null)
            {
                MessageBox.Show("Markera en produktgrupp att ändra", "Ingen produktgrupp vald");
                return;
            }

            // Initilize a new window for editing a group
            ProductGroupCategory pgc = new ProductGroupCategory(SelectedProductGroup);

            // Show the window
            pgc.ShowDialog();

            // If the users presses OK, update the item
            if (pgc.DialogResult == true)
            {
                // Update the database context
                ProductGroupManagement.Instance.UpdateProductGroup();
            }
            else
            {
                // The user pressed cancel, revert changes
                ProductGroupManagement.Instance.ResetProductGroup(SelectedProductGroup);
            }
        }
        /// <summary>
        /// Add a new product group
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            // Initilize a new window for adding a new account
            ProductGroupCategory pgc = new ProductGroupCategory(true);

            // Show the window
            pgc.ShowDialog();

            // If the users presses OK, add the new user
            if (pgc.DialogResult.Equals(true))
            {
                // Add the category to the database
                ProductGroupManagement.Instance.AddProductGroup(pgc.ProductGroup);
            }
        }