protected void btnDelete_Click(object sender, EventArgs e)
    {
        if (RadTreeView1.SelectedNode == null)
        {
            ShowError("Selecione uma categoria!");
            return;
        }
        ProductManager manager = new ProductManager(this);
        ProductPart productPart = manager.GetProductPart(Convert.ToInt32(RadTreeView1.SelectedNode.Value));

        try
        {
            manager.DeleteProductPart(productPart);
        }
        catch (Exception ex)
        {
            ShowError(ex.Message.ToString());
            return;
        }

        BindTree();
    }