ListBox Weiterentwicklung

[Alex_ITA01]

OK das mit den 2 Eigenschaften und dem + davor habe ich hinbekommen nur will ich jetzt wenn visible auf True gesetzt wird, auch die Horizontale Scrollbar angezeigt wird
Nur bei mir kennt er Handle nicht und ich weiß nicht wie ich es 'bekomme'

Delphi-Quellcode:

unit ColorListBox1;

interface

uses
  SysUtils, Classes, Controls, StdCtrls, Graphics, Windows, Messages;

type
  TScroll = class(TGraphicsObject)
  private
    FVisible  : Boolean;
    FLength   : Integer;
    procedure SetVisible(Value  : Boolean);
    procedure SetLength (Value  : Integer);
  protected

  public
    constructor  Create;
  published
    property Visible : Boolean read FVisible write SetVisible default False;
    property Length  : Integer read FLength  write SetLength  default 0;
  end;

  MyColorListBox1 = class(TListBox)
  private
    { Private-Deklarationen }
    FScrollbar : TScroll;
    procedure SetScrollBar (Value : TScroll);
  protected
    { Protected-Deklarationen }
  public
    { Public-Deklarationen }
    constructor Create(AOwner:TComponent); override;
    destructor Destroy; override;
  published
    { Published-Deklarationen }
    property Scrollbar  : TScroll read FScrollbar write SetScrollBar;
  end;

procedure Register;
{ ----------------------------------------------------------------------------- }
implementation
{ ----------------------------------------------------------------------------- }
procedure Register;
begin
  RegisterComponents('Beispiele', [MyColorListBox1]);
end;
{ ----------------------------------------------------------------------------- }
{ ColorListBox1 }
{ ----------------------------------------------------------------------------- }
constructor MyColorListBox1.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  Width   := 100;
  Height  := 100;
  FScrollbar := TScroll.Create;
end;
{ ----------------------------------------------------------------------------- }
destructor MyColorListBox1.Destroy;
begin
  FScrollbar.Free;
  inherited Destroy;
end;
{ ----------------------------------------------------------------------------- }
{ TScroll }
{ ----------------------------------------------------------------------------- }
constructor TScroll.Create;
begin
  inherited Create;
  FVisible := False;
  FLength  := 0;
end;
{ ----------------------------------------------------------------------------- }
procedure TScroll.SetLength(Value: Integer);
begin
  if Value <> 0 then
    FLength := Value;
end;
{ ----------------------------------------------------------------------------- }
procedure TScroll.SetVisible(Value: Boolean);
begin
  if Value = True then
  begin
    FVisible := Value;
  end;
  if FLength = 0 then
    FLength := 100;
//  SendMessage(FHandle, LB_SetHorizontalExtent,FLength,Longint(0));
{ Handle undefiniert !!!!! }
end;
{ ----------------------------------------------------------------------------- }
procedure MyColorListBox1.SetScrollBar(Value: TScroll);
begin
  if Value.FVisible = True then
  begin
    FScrollbar := Value;
    if Value.FLength = 0 then
      Value.FLength := 10;
    SendMessage(Handle, LB_SetHorizontalExtent,Value.FLength,Longint(0));
  end;
end;
{ ----------------------------------------------------------------------------- }
end.

Könnte ihr mir bitte helfen???