rv = ds->IsCommandEnabled(aSources, aCommand, aArguments, &enabled);
rv = mDataSources[i]->IsCommandEnabled(aSources, aCommand, aArguments, &enabled);
CompositeDataSourceImpl::IsCommandEnabled(nsISupportsArray/*<nsIRDFResource>*/* aSources,                                          nsIRDFResource*   aCommand,                                          nsISupportsArray/*<nsIRDFResource>*/* aArguments,                                          PRBool* aResult){    nsresult rv;    for (PRInt32 i = mDataSources.Count() - 1; i >= 0; --i) {        nsIRDFDataSource* ds = NS_STATIC_CAST(nsIRDFDataSource*, mDataSources[i]);        PRBool enabled = PR_TRUE;        rv = ds->IsCommandEnabled(aSources, aCommand, aArguments, &enabled);        if (NS_FAILED(rv) && (rv != NS_ERROR_NOT_IMPLEMENTED))        {        	return(rv);        }        if (! enabled) {            *aResult = PR_FALSE;            return(NS_OK);        }    }    *aResult = PR_TRUE;    return(NS_OK);}