private void quảnLýNhàCungCấpToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmNguyenLieu f = new frmNguyenLieu();

            f.MdiParent = this;
            f.Show();
        }
        public frmDanhMuc()
        {
            InitializeComponent();
            frmNguyenLieu f = new frmNguyenLieu();

            f.MdiParent = this;
            f.Show();
        }