public static extern IntPtr SendMessage(HandleRef hWnd, ComCtl32.HeaderMessage message, [MarshalAs(UnmanagedType.SysInt)] int wParam, [In, Out] ComCtl32.HDHITTESTINFO hittest);
public static extern IntPtr SendMessage(HandleRef hWnd, ComCtl32.HeaderMessage message, [MarshalAs(UnmanagedType.SysInt)] int wParam, [In, Out] ComCtl32.HDLAYOUT layout);