winform 中一个窗口嵌套到另一个窗口

 {
        public Frm_Dispense_Outside()
        {
            InitializeComponent();
            Frm_Dispense_Check fdc = new Frm_Dispense_Check();
            fdc.TopLevel = false;
            fdc.Dock = DockStyle.Fill;
            fdc.FormBorderStyle = FormBorderStyle.None;
            this.Controls.Clear();
            this.Controls.Add(fdc);
            fdc.Show();

        }