anchor.diff:  
   procedure TMainForm.tvContentsChange(Sender: TObject);
   begin
  +  if CurrentOpenFiles.Count = 0 then
  +    Exit;
  +
     DisplayTopic(nil);
   end;
   
   procedure TMainForm.edSearchTextKeyPress(Sender: TObject; var KeyCode: word;
     var ShiftState: TShiftState; var Consumed: boolean);
   begin
  +  if CurrentOpenFiles.Count = 0 then
  +    Exit;
  +
     if (KeyCode = keyReturn) or (KeyCode = keyPEnter) then
     begin
       Consumed := True;
  
positive.code: procedure TMainForm.IndexSearchEditKeyPress(Sender: TObject; var KeyCode: word;
    var ShiftState: TShiftState; var Consumed: boolean);
  begin
    if (KeyCode = keyEnter) or (KeyCode = keyPEnter) then
    begin
      Consumed := True;
  
negative.code:   fpgImages.AddMaskedBMP(
      'dv.arrowdown', @usr_arrow_down,
      sizeof(usr_arrow_down), 0, 0);
  end;
  
  destructor TMainForm.Destroy;
  