message: python: fix trackbar warning
diff: @@ -1971,15 +1971,23 @@ static void OnChange(int pos, void *param)
  }
  #ifdef HAVE_OPENCV_HIGHGUI
  +// workaround for #20408, use nullptr, set value later
  +static int _createTrackbar(const String &trackbar_name, const String &window_name, int value, int count,
  + TrackbarCallback onChange, PyObject* py_callback_info)
  +{
  + int n = createTrackbar(trackbar_name, window_name, NULL, count, onChange, py_callback_info);
  + setTrackbarPos(trackbar_name, window_name, value);
  + return n;
  +}
  static PyObject *pycvCreateTrackbar(PyObject*, PyObject *args)
  {
  PyObject *on_change;
  char* trackbar_name;
  char* window_name;
  - int *value = new int;
  + int value;
  int count;
  - if (!PyArg_ParseTuple(args, "ssiiO", &trackbar_name, &window_name, value, &count, &on_change))
  + if (!PyArg_ParseTuple(args, "ssiiO", &trackbar_name, &window_name, &value, &count, &on_change))
  return NULL;
  if (!PyCallable_Check(on_change)) {
  PyErr_SetString(PyExc_TypeError, "on_change must be callable");
  @@ -1998,7 +2006,7 @@ static PyObject *pycvCreateTrackbar(PyObject*, PyObject *args)
  {
  registered_callbacks.insert(std::pair<std::string, PyObject*>(name, py_callback_info));
  }
  - ERRWRAP2(createTrackbar(trackbar_name, window_name, value, count, OnChange, py_callback_info));
  + ERRWRAP2(_createTrackbar(trackbar_name, window_name, value, count, OnChange, py_callback_info));
  Py_RETURN_NONE;
  }
  