Как остановить все потоки разом?

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;
 
type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
HThread: THandle;
ThreadID: DWORD;
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure PaintEllipse;
const D=30;
var
x, y: integer;
Direction: Boolean;
dirx, diry: -1..1;
dc: hdc;
Rect: TRect;
begin
dc:=getdc(Form1.Handle);
x:=10; y:=10;
Direction:=True;
dirx:=1; diry:=1;
repeat
with Rect do
begin
Left :=x;
Top:=y;
Right:=x+D;
Bottom:=y+D;
end;
FillRect (dc, Rect, COLOR_BTNFACE+1);
if Direction then x:=x+dirX else y:=y+dirY;
if x>Form1.ClientWidth-10-D then
begin
dirX:=-1; Direction:=False; x:=Form1.ClientWidth-10-D;
end;
if x<10 then
begin
dirX:=1; Direction:=False; x:=10;
end;
if y>Form1.ClientHeight-10-D then
begin
Direction:=True; dirY:=-1; y:=form1.ClientHeight-10-D;
end;
if y<10 then
begin
Direction:=True; dirY:=1; y:=10;
end;
Ellipse (dc, x, y, x+D, y+D);
Sleep (5);
until False;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
HThread:=CreateThread (nil, 0, @PaintEllipse, nil, 0, ThreadId);
end;
 
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  If button = MbRight then
   TerminateThread(HThread,ThreadId);
end;
end.

var
  Form1: TForm1;
  TerminateThread: boolean;
 
implementation
 
{$R *.dfm}
 
procedure PaintEllipse;
const
  D = 30;
var
  x, y: integer;
  Direction: Boolean;
  dirx, diry: -1..1;
  dc: hdc;
  Rect: TRect;
begin
  dc := getdc(Form1.Handle);
  x := 10;
  y := 10;
  Direction := True;
  dirx:=1;
  diry:=1;
  repeat
...
  until TerminateThread;
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  TerminateThread := false;
//  HThread:=
  CreateThread (nil, 0, @PaintEllipse, nil, 0, ThreadId);
end;
 
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  If button = MbLeft then begin
    TerminateThread := false;
    CreateThread (nil, 0, @PaintEllipse, nil, 0, ThreadId);
  end;
  If button = MbRight then
    TerminateThread := true;
//   TerminateThread(HThread,ThreadId);
end;
 
procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  TerminateThread := true;
end;
 
end.