anchor.diff:      property    ScrollStep: integer read FScrollStep write FScrollStep default 1;
       property    ShowHint;
       property    ShowPosition: boolean read FShowPosition write SetShowPosition default False;
  +    property    SliderLength: integer read FSliderLength write SetSliderLength default 11;
       property    TabOrder;
       property    TextColor;
       property    OnChange;
  
positive.code:   private
      FScrollStep: integer;
      FShowPosition: boolean;
      FSliderPos: TfpgCoord;
      FSliderLength: TfpgCoord;
      FSliderDragging: boolean;
      FSliderDragPos: TfpgCoord;
      FSliderDragStart: TfpgCoord;
      FMousePosition: TPoint;
      FFont: TfpgFont;
      procedure   SetShowPosition(const AValue: boolean);
      function    GetTextWidth: TfpgCoord;
    protected
      procedure   HandleLMouseDown(x, y: integer; shiftstate: TShiftState); override;
      procedure   HandleLMouseUp(x, y: integer; shiftstate: TShiftState); override;
      procedure   HandleMouseMove(x, y: integer; btnstate: word; shiftstate: TShiftState); override;
  
negative.code:     Result := 0;
  end;
  
  procedure TfpgTrackBar.SetSliderLength(AValue: integer);
  begin
    if FSliderLength = AValue then
      Exit;
    FSliderLength := AValue;
    RePaint;
  end;
  
  procedure TfpgTrackBar.HandleLMouseDown(x, y: integer; shiftstate: TShiftState);
  var
    tw: TfpgCoord;
  