public static extern bool ScreenToClient(IntPtr hWnd, ref POINT lpPoint);
public static extern IntPtr WindowFromPoint(POINT point);
public static extern bool GetCursorPos(ref POINT lpPoint);
public static extern bool ScreenToClient(IntPtr hWnd, ref POINT lpPoint);
public static extern IntPtr WindowFromPoint(POINT point);
public static extern bool GetCursorPos(ref POINT lpPoint);