ret = pPrefService->SavePrefFile(nsnull);
ret = pPrefService->SavePrefFile();
SI_SetBoolPref(const char * prefname, PRBool prefvalue) {  nsresult ret;  nsCOMPtr<nsIPref> pPrefService = do_GetService(NS_PREF_CONTRACTID, &ret);  if (!NS_FAILED(ret)) {    ret = pPrefService->SetBoolPref(prefname, prefvalue);    if (!NS_FAILED(ret)) {      ret = pPrefService->SavePrefFile(nsnull);     }  }}