anchor.diff:  function TfpgListBoxStrings.Add(const s: String): Integer;
   begin
     Result := inherited Add(s);
  +  if UpdateCount > 0 then
  +      Exit;
     if Assigned(ListBox) and (ListBox.HasHandle) then
     begin
       ListBox.UpdateScrollBar;
  
positive.code: 
  { TfpgListBoxStrings }
  
  procedure TfpgListBoxStrings.SetUpdateState(Updating: Boolean);
  begin
    inherited SetUpdateState(Updating);
    // do nothing extra for now
  end;
  
  constructor TfpgListBoxStrings.Create(AListBox: TfpgTextListBox);
  begin
    inherited Create;
  
negative.code: procedure TfpgListBoxStrings.Clear;
  begin
    inherited Clear;
    if UpdateCount > 0 then
        Exit;
    ListBox.FocusItem := -1;
    ListBox.UpdateScrollBar;
    ListBox.Invalidate;
  