protected override void OnHandleCreated(EventArgs e)
{
base.OnHandleCreated(e);
// Get a handle to a copy of this form's system (window) menu
var hSysMenu = User32.GetSystemMenu(Handle, false);
// Add a separator
User32.AppendMenu(hSysMenu, User32.MfSeparator, 0, string.Empty);
// Add the About menu item
User32.AppendMenu(hSysMenu, User32.MfString, SysMenuAboutId, "&About");
}