public static extern int MapWindowPoints(IntPtr hWnd, IntPtr hWndTo, ref POINT pt, int cPoints);
public static extern IntPtr ChildWindowFromPointEx(IntPtr hParent, POINT pt, ChildFromPointFlags flags);
public static extern int MapWindowPoints(IntPtr hWnd, IntPtr hWndTo, ref POINT pt, int cPoints);
public static extern IntPtr ChildWindowFromPointEx(IntPtr hParent, POINT pt, ChildFromPointFlags flags);