Как создать в listbox события OnChange и OnChanging?

INTERFACE

USES
  SysUtils, WinTypes, Messages, Classes, Controls, Graphics, Forms,
  Menus, StdCtrls;

type
  TMyListBox = Class(TListBox)
    private
      FOnChange : TNotifyEvent;
      FLastSel : integer;
      procedure Click; override;
    protected
      procedure Change; Virtual;
    published
      property pan> OnChange : TNotifyEvent read FOnChange write FOnChange;
    public
      constructor create(AOwner : TComponent); override;
  end;

procedure Register;

IMPLEMENTATION

procedure TMyListBox.Change;
begin
  FLastSel := ItemIndex;
  if assigned(FOnChange) then FOnChange(self);
end;

procedure TMyListBox.Click;
begin
  inherited Click;
  if FLastSel <> ItemIndex then
     Change;
end;

constructor TMyListBox.Create;
begin
  Inherited Create(AOwner);
  FLastSel := -1;
end;

procedure Register;
begin
  RegisterComponents(‘MyComponents’,[TMyListBox]);
end;

end.Syhi-подсветка кода