(*accountList) += key;
(*accountList).Append(key);
nsMsgAccountManager::getAccountList(nsISupports *element, void *aData){  nsresult rv;  nsCAutoString* accountList = (nsCAutoString*) aData;  nsCOMPtr<nsIMsgAccount> account = do_QueryInterface(element, &rv);  if (NS_FAILED(rv)) return PR_TRUE;    nsXPIDLCString key;  rv = account->GetKey(getter_Copies(key));  if (NS_FAILED(rv)) return PR_TRUE;  if ((*accountList).IsEmpty())    (*accountList) += key;  else {    (*accountList) += ',';    (*accountList) += key;  }  return PR_TRUE;}