public static extern bool GetCursorPos(ref POINT lpPoint);
public static extern int MapWindowPoints(IntPtr hWnd, IntPtr hWndTo, ref POINT pt, int cPoints);
public static extern bool ClientToScreen(IntPtr hWnd, ref POINT lpPoint);
public static extern bool ScreenToClient(IntPtr hWnd, ref POINT lpPoint);
public static extern IntPtr WindowFromPoint(POINT point);