在Tlistbox里用小键盘的上下键移动触发 的事件是什么？该如何解决

procedure TWinControl.CNKeyDown(var Message: TWMKeyDown);
var
  Mask: Integer;
begin
  with Message do
  begin
    Result := 1;
    if IsMenuKey(Message) then Exit;
    if not (csDesigning in ComponentState) then
    begin
      if Perform(CM_CHILDKEY, CharCode, Integer(Self)) <> 0 then Exit;
      Mask := 0;
      case CharCode of
        VK_TAB:
          Mask := DLGC_WANTTAB;
        VK_LEFT, VK_RIGHT, VK_UP, VK_DOWN:
          Mask := DLGC_WANTARROWS;
        VK_RETURN, VK_EXECUTE, VK_ESCAPE, VK_CANCEL:
          Mask := DLGC_WANTALLKEYS;
      end;
      if (Mask <> 0) and
        (Perform(CM_WANTSPECIALKEY, CharCode, 0) = 0) and
        (Perform(WM_GETDLGCODE, 0, 0) and Mask = 0) and
        (GetParentForm(Self).Perform(CM_DIALOGKEY,
        CharCode, KeyData) <> 0) then Exit;
    end;
    Result := 0;
  end;
end;