private void btnShowLoaiSP_Click(object sender, EventArgs e)
        {
            FormLoaiSanPham f = new FormLoaiSanPham();

            Hide();
            f.ShowDialog();
            Show();
        }
        private void btnSanPham_addLoaiSP_Click(object sender, EventArgs e)
        {
            FormLoaiSanPham f = new FormLoaiSanPham();

            f.Show();
        }