Persist ActiveX Controls At Runtime

I was writing a piece of code to store and load user preferences and wanted to persist the properties of some ActiveX controls on my dialog. The following procedure seems to do the job rather nicely.

BOOL PersistActiveX(CArchive& ar, CWnd* pActiveX)
{
 ASSERT(pActiveX);

 HRESULT hr = E_FAIL;

 // Create an archive stream
 CArchiveStream stm(&ar);
 LPPERSISTSTREAMINIT pPersStm = NULL;
 LPUNKNOWN lpUnk = pActiveX->GetControlUnknown();

 if(lpUnk)
 {
  // We have the IUnknown interface, so 
  // get the IPersistStreamInit
  lpUnk->QueryInterface(IID_IPersistStreamInit, 
                        (LPVOID*)&pPersStm);

  if(pPersStm)
  {
   // We have the relevant interface so load or save the data
   // based on the type of archive we have.
   if(ar.IsLoading())
   {
    hr = pPersStm->Load(&stm);
   }
   else
   {
    hr = pPersStm->Save(&stm, FALSE);
   }
  }

  // Must release the interface
  pPersStm->Release();
 }

 return SUCCEEDED(hr);
}
This can then be called simply by doing the following:
PersistActiveX(ar, GetDlgItem(IDC_SOMEACTIVEX));