public PanelProduct CreatePanel(Product product)
        {
            PanelProduct panel = null;

            if (product is Book)
            {
                panel = new BookPanel((Book)product);
            }
            else if (product is Magazine)
            {
                panel = new MagazinePanel((Magazine)product);
            }
            else
            {
                panel = new MusicCdPanel((MusicCD)product);
            }

            return(panel);
        }
        private void cmbCategory_SelectedIndexChanged(object sender, EventArgs e)
        {
            flpnlItems.Controls.Clear();
            CurrentProductList.Clear();

            foreach (var item in (List <Product>)productList[cmbProduct.SelectedIndex])
            {
                if (item.Category == cmbCategory.SelectedItem.ToString())
                {
                    CurrentProductList.Add(item);
                    PanelProduct pnl = panelCreator.CreatePanel(item);
                    flpnlItems.Controls.Add(pnl);
                }
                else if (cmbCategory.SelectedItem.ToString() == "Hepsi")
                {
                    CurrentProductList.Add(item);
                    PanelProduct pnl = panelCreator.CreatePanel(item);
                    flpnlItems.Controls.Add(pnl);
                }
            }
        }