WM_NCLBUTTONUP 메시지에서 DC로 출력할 수 없나요?

TCHAR nclbuffer[1024];
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
  switch(message) {
    //이상 코드생략....
    case WM_NCLBUTTONUP:
      {
        RECT winRect;
        GetWindowRect(hwnd, &winRect);
        HRGN winRgn=CreateRectRgn(winRect.left, winRect.top, winRect.right, winRect.bottom);
        HDC mainHdc=GetDCEx(hwnd, winRgn, DCX_WINDOW | DCX_INTERSECTRGN);
        _stprintf(nclbuffer, _T("%s WM_NCLBUTTONUP"), nclbuffer);
        TextOut(mainHdc, 10, 5, nclbuffer, _tcslen(nclbuffer));
        ReleaseDC(hwnd, mainHdc);
      }
      return 0;
      //이하 코드생략....
  }
  return DefWindowProc(hwnd, message, wparam, lparam);
}