private void InitSystemMenu() { var systemMenu = new SystemMenu(this, this); var resizeMenuItem = systemMenu.CreateMenuItem("&Resize..."); resizeMenuItem.Clicked += delegate { new FormResizeWindow(this).ShowDialog(this); }; var alwaysOnTopMenuItem = systemMenu.CreateMenuItem("Always on &top"); alwaysOnTopMenuItem.Clicked += delegate { var alwaysOnTop = !alwaysOnTopMenuItem.Checked; TopMost = alwaysOnTop; alwaysOnTopMenuItem.Checked = alwaysOnTop; systemMenu.UpdateMenu(alwaysOnTopMenuItem); }; uint pos = 5; systemMenu.InsertSeparator(pos++); systemMenu.InsertMenu(pos++, resizeMenuItem); systemMenu.InsertMenu(pos++, alwaysOnTopMenuItem); }