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 );