anchor.diff:  filling({button, Button, ReplyTo}=Cmd, #state{bufCnt=0}=State0) ->
       % too quick, defer request .. when we have the first block of data 
       State1 = reply_stack(filling, ReplyTo, State0),
  +    State2 = prefetch(filling,State1),
       ?NoDbLog(debug, [], "filling stack ~p", [Button]),
  -    {next_state, filling, State1#state{stack=Cmd}};
  +    {next_state, filling, State2#state{stack=Cmd}};
   filling({button, <<"...">>, ReplyTo}, #state{dirtyCnt=DC}=State0) when DC==0 ->
       % close fetch and clear buffers, schedule tail mode
       State1 = reply_stack(filling, ReplyTo, State0),
  
positive.code:     if
          (BufCnt == 0) andalso (SN == filling) ->
              ?Debug("~p waiting for the fetch to complete ~p", [SN, <<">">>]),
              State0#state{stack={button,<<">">>,ReplyTo}};
          (BufCnt == 0) ->
              %% no data, serve empty gui
              State1 = prefetch(SN,State0),
  
negative.code: serve_stack( _, #state{stack=undefined}=State) -> 
      % no stack, nothing .. do
      State;
  serve_stack(completed, #state{nav=ind,bufBot=B,guiBot=B,guiCol=true,stack={button,Button,RT}}=State0) when
        Button =:= <<">">>;
        Button =:= <<">>">>;
        Button =:= <<">|">>;
        Button =:= <<">|...">>;
        Button =:= <<"more">> ->
      ?NoDbLog(debug, [], "~p stack exec ~p when guiCol true", [completed,Button]),
      serve_bot(completed,<<>>,State0#state{stack=undefined,replyToFun=RT});
  serve_stack( _, #state{nav=ind,bufBot=B,guiBot=B}=State) -> 
      % gui is current at the end of the buffer, no new interesting data, nothing .. do
      State;
  