public static extern int SendMessage(IntPtr hWnd, HeaderControlMessages msg, int wParam, int lParam);
IntPtr SendMessage(IntPtr hWnd, HeaderControlMessages wMsg, IntPtr wParam, HDITEM lParam);
public static extern void SendMessage(IntPtr hWnd, HeaderControlMessages msg, int wParam, ref HD_HITTESTINFO hti);
public static extern void SendMessage(IntPtr hWnd, HeaderControlMessages msg, int wParam, ref HDITEM lParam);