UINT APIENTRY OFNNewHookProc(HWND hdlg, UINT uiMsg, WPARAM wParam,
    LPARAM lParam);

OPENFILENAME	Ofn;
 memset(&Ofn,  0 , sizeof(Ofn));
 Ofn.lStructSize = sizeof(Ofn);
 //Ofn.hInstance = hInstance;
 Ofn.Flags = OFN_HIDEREADONLY/*|OFN_ENABLETEMPLATE*/|OFN_EXPLORER|OFN_ENABLEHOOK;
 Ofn.lpstrFilter = Filter;
 Ofn.nFilterIndex =  1 ;
 Ofn.lpstrFile = Path;
 Ofn.nMaxFile =  256 ;
 Ofn.lpstrFileTitle = Buf;
 Ofn.nMaxFileTitle =  256 ;
 Ofn.lpstrTitle = "Заголовок";
 Ofn.lpfnHook = OFNNewHookProc;

UINT APIENTRY OFNNewHookProc(HWND hdlg, UINT uiMsg, WPARAM wParam,
    LPARAM lParam)
{
 // Здесь добавляем, удаляем и т.д. только осторожно
}