if (mTxnMgr) srcArray->InsertElementAt(mTxnMgr, 0);
nsMessenger::DoCommand(nsIRDFCompositeDataSource* db, const nsACString& command,                       nsISupportsArray *srcArray,                        nsISupportsArray *argumentArray){	nsresult rv;    nsCOMPtr<nsIRDFService> rdfService(do_GetService(kRDFServiceCID, &rv));	if(NS_FAILED(rv))		return rv;	nsCOMPtr<nsIRDFResource> commandResource;	rv = rdfService->GetResource(command, getter_AddRefs(commandResource));	if(NS_SUCCEEDED(rv))	{		rv = db->DoCommand(srcArray, commandResource, argumentArray);	}	return rv;}