ich verzweifle noch.... ich bekomme immer den "Debug Fehler 3"
was ist hier faul ???

class gui_window_class
{
 protected:
   static LRESULT CALLBACK win32_static_on_event (HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
   LRESULT CALLBACK win32_on_event (UINT uMsg, WPARAM wParam, LPARAM lParam);

 public:
   gui_window_class (void);
   ~gui_window_class ();

   void install (void);

   HWND hWnd;
};

void gui_window_class :: install ()
{
// .....

      if (!CreateWindow (win_class_name, '\0', dwStyle, Left, Top, Width, Height, hParent, NULL, hInstance, (void *)this))
      {
         MessageBox(NULL, TEXT ("Failed to create the window."), TEXT ("Error"), MB_OK | MB_ICONEXCLAMATION);
      }
}

LRESULT CALLBACK gui_window_class :: win32_static_on_event (HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
   gui_window_class* wnd = NULL;

   if(uMsg == WM_CREATE) 
   {
      LPCREATESTRUCT cs = (LPCREATESTRUCT)(lParam); 
      if(!cs->lpCreateParams) MessageBox(NULL, TEXT ("Debug Fehler 1"), TEXT ("Error"), MB_OK | MB_ICONEXCLAMATION);
      else SetWindowLong(hWnd, GWL_USERDATA, (long)(cs->lpCreateParams));

      wnd = (gui_window_class *)(cs->lpCreateParams);
      if(!wnd) MessageBox(NULL, TEXT ("Debug Fehler 2"), TEXT ("Error"), MB_OK | MB_ICONEXCLAMATION);
      else wnd->hWnd = hWnd;
   }
   else
   {
      wnd = (gui_window_class *)(GetWindowLong(hWnd, GWL_USERDATA));
      if (!wnd) MessageBox(NULL, TEXT ("Debug Fehler 3"), TEXT ("Error"), MB_OK | MB_ICONEXCLAMATION);
   }

   if (wnd) return wnd->win32_on_event(uMsg, wParam, lParam);
   else return 0L; // I think, is it right ????????????
}

LRESULT CALLBACK gui_window_class :: win32_on_event (UINT uMsg, WPARAM wParam, LPARAM lParam)
{
   switch (uMsg)
   {
      case WM_CLOSE:
      {
         PostQuitMessage(0);
         return 0L;
      }
      default:
      {
         return DefWindowProc (this->hWnd, uMsg, wParam, lParam);
      }
   }
}