unit Listbob;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, StdCtrls;

type
  TListBob = class(tlistbox)
  private
    { Private declarations }
    FOnHScroll: TNotifyEvent;
    FOnVScroll: TNotifyEvent;
  protected
    { Protected declarations }
    procedure WMHScroll(var Message: TWMHScroll); message WM_HSCROLL;
    procedure WMVScroll(var Message: TWMVScroll); message WM_VSCROLL;
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
  published
    { Published declarations }
    property OnHScroll: TNotifyEvent read FOnHScroll write FOnHScroll;
    property OnVScroll: TNotifyEvent read FOnVScroll write FOnVScroll;
  end;

procedure Register;

implementation

constructor TListBob.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FOnHScroll := nil;
  FOnVScroll := nil;
end;

procedure TListBob.WMHScroll(var Message: TWMHScroll);
{ помните что данное сообщение вызывается дважды!! }
begin
  if Assigned(FOnHScroll) then
    FOnHScroll(Self);
  DefaultHandler(Message);
end;

procedure TListBob.WMVScroll(var Message: TWMHScroll);
{ помните что данное сообщение вызывается дважды!! }
begin
  if Assigned(FOnVScroll) then
    FOnVScroll(Self);
  DefaultHandler(Message);
end;

procedure Register;
begin
  RegisterComponents('Dr.Bob', [TListBob]);
end;

end.