anchor.diff:    r: TfpgRect;
     tw: TfpgCoord;
   begin
  -  Canvas.BeginDraw;
     Canvas.Clear(FBackgroundColor);
     Canvas.SetColor(FBackgroundColor);
   
  
positive.code:     FPosition := FMax;
  
    if Visible then
      DrawSlider(True);
  
    if Assigned(FOnChange) then
      FOnChange(self, FPosition);
  
negative.code:       DrawSlider(round(2 + FSliderSize div 2 + linepos * position));
      end;
    end;  { if/else }
  end;
  
  procedure TfpgTrackBarExtra.HandleLMouseUp(x, y: integer; shiftstate: TShiftState);
  