windows form 如何嵌套窗体

            PTC ptc = new PTC();
            ptc.TopLevel = false;//不是项层窗体
            ptc.FormBorderStyle = FormBorderStyle.None;//没有标题栏
            ptc.Visible = true;//显示
            this.PTCPanel.Controls.Add(ptc);//panel1嵌入from2

其中ptc是要被嵌套的窗体，PTCPanel是一个panel，用来放置ptc。