unsigned int WINAPI Browser::GoBackThreadProc(LPVOID param) {
  HRESULT hr = ::CoInitialize(NULL);
  IWebBrowser2* browser;
  LPSTREAM message_payload = reinterpret_cast<LPSTREAM>(param);
  hr = ::CoGetInterfaceAndReleaseStream(message_payload,
                                        IID_IWebBrowser2,
                                        reinterpret_cast<void**>(&browser));
  hr = browser->GoBack();
  return 0;
}
void Win32WebControl::goBack() const
{
    _webBrowser2->GoBack();
}