"Ulrich Czekalla" <ulrich.czekalla at utoronto.ca> wrote: > + if (control->hwnd) > + { > + WNDPROC oldproc = (WNDPROC) SetWindowLongPtrW(control->hwnd, GWLP_WNDPROC, > + (LONG)MSIRadioGroup_WndProc); Then it's better to cast to LONG_PTR instead of LONG. -- Dmitry.