mTxnMgr->Undo();
{ nsCOMPtr<nsITransaction> txn; rv = mTxnMgr->PeekUndoStack(getter_AddRefs(txn)); if (NS_SUCCEEDED(rv) && txn) { NS_STATIC_CAST(nsMsgTxn*, NS_STATIC_CAST(nsITransaction*, txn.get()))->SetMsgWindow(msgWindow); } mTxnMgr->UndoTransaction(); }
nsMessenger::Undo(){  nsresult rv = NS_OK;  if (mTxnMgr)  {    PRInt32 numTxn = 0;    rv = mTxnMgr->GetNumberOfUndoItems(&numTxn);    if (NS_SUCCEEDED(rv) && numTxn > 0)      mTxnMgr->Undo();  }  return rv;}