[helper999999]

так правильно будет?:

Код:

unit Unit1;

interface

uses  windows,
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    ListBox1: TListBox;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public

    { public declarations }
  end;

var tid: TThreadID;
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure tp(hWnd: HWND; uMsg: UINT; idEvent: UINT_PTR; dwTime: DWORD);
  stdcall;
begin
  form1.ListBox1.Items.Append('11');
end;

procedure tt;
begin
 SetTimer(Form1.Handle,1,100,@tp);
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
 BeginThread(nil,0,@tt,nil,0,tid);
end;


end.

Тут отображено работа таймера в цикле.