public static extern bool ScreenToClient(IntPtr hWnd, ref POINT lpPoint);
public static extern bool ClientToScreen(IntPtr hWnd, ref POINT lpPoint);
public static extern bool GetCaretPos(out POINT lpPoint);
public static extern bool UpdateLayeredWindow(IntPtr hwnd
, IntPtr hdcDst
, ref POINT pptDst
, ref SIZE psize
, IntPtr hdcSrc
, ref POINT pptSrc
, uint crKey
, [In] ref BLENDFUNCTION pblend
, uint dwFlags
);