pannel加载form

 panel2.Controls.Clear();
            frm.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            frm.ShowIcon = false;
            frm.ShowInTaskbar = false;
            frm.BackColor = Color.White;
            //要将是否顶级控件设置为false，否则会报错
            frm.TopLevel = false;
            frm.Dock = DockStyle.Fill;
            panel2.Controls.Add(frm);

            ////TabPage tab = new TabPage(frm.Name);
            ////tab.Controls.Add(frm);
            ////tabControl1.TabPages.Add(tab);
            ////tab.Show();
            frm.Show();
            frm.BringToFront();
            frm.Focus();