Возврат значения из класса TThread

[Alter]

Есть простой класс на основе TThread. В примере должен вернуть строку.
Прототип http://www.interface.ru/home.asp?artId=23280

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  Pstring = ^string;

type TMyThread = class(TThread)
  private
   FTxt :string;
  protected
   procedure Execute; override;
  public
    constructor Create(Txt :Pstring; CreatePaused :Boolean=True);
    destructor Destroy; override;
  published

end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
   MyThr :TMyThread;
   FEndThr :Boolean;
   procedure ThrTerminate(Sender :TObject);
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(Txt: Pstring; CreatePaused: Boolean);
begin
 inherited Create(CreatePaused);
 Priority := tpNormal;
 FreeOnTerminate := True;
 Pointer(FTxt) := Txt;
end;

destructor TMyThread.Destroy;
begin
 inherited Destroy;
end;

procedure TMyThread.Execute;
begin
  try
 FTxt := 'Какой-то текст';
  finally
// Pointer(FTxt) := Nil;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Buf :Pstring;
begin
 Edit1.Text := '';
  //
 New(Buf);
 MyThr := TMyThread.Create(Buf, True);
  try
    try
 FEndThr := False; // запущенно
 MyThr.OnTerminate := ThrTerminate;
 MyThr.Resume;
// MyThr.WaitFor;
 while FEndThr = False do
  Application.ProcessMessages();
  //
 Edit1.Text := Buf^;
 ShowMessage('Завершенно');
    except
 Edit1.Text := 'Непредвиденная ошибка';
    end;
  finally
 Dispose(Buf);
 FEndThr := True;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 FEndThr := True;
end;

procedure TForm1.ThrTerminate(Sender: TObject);
begin
 FEndThr := True;
end;

end.

Замучался, несколько дней "это" пытало меня. Уже и не знаю что тут не так, при закрытии приложения AV, если был ранее запущен поток.

[GunSmoker]

PString? OMFG!

Читаем мат-часть.

type
  TMyThread = class(TThread)
  private
    FTxt: string;
  protected
    procedure Execute; override;
  public
    constructor Create(const ATerminateHandler: TNotifyEvent = nil);
    property StrResult: String read FTxt;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(const ATerminateHandler: TNotifyEvent);
begin
  inherited Create(False);

  Priority := tpNormal;
  FreeOnTerminate := False;
  OnTerminate := ATerminateHandler;
end;

procedure TMyThread.Execute;
begin
  FTxt := 'Какой-то текст';
  Sleep(1000);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  MyThr: TMyThread;
begin
  Edit1.Text := '';

  MyThr := TMyThread.Create;
  try
    MyThr.WaitFor;

    Edit1.Text := MyThr.StrResult;
  finally
    FreeAndNil(MyThr);
  end;

  ShowMessage('Завершенно');
end;

Или:

type
  TMyThread = class(TThread)
  private
    FTxt: string;
  protected
    procedure Execute; override;
  public
    constructor Create(const ATerminateHandler: TNotifyEvent = nil);
    property StrResult: String read FTxt;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    procedure NotifyMainThread(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(const ATerminateHandler: TNotifyEvent);
begin
  inherited Create(False);

  Priority := tpNormal;
  FreeOnTerminate := False;
  OnTerminate := ATerminateHandler;
end;

procedure TMyThread.Execute;
begin
  try
    FTxt := 'Какой-то текст';
    Sleep(1000);
  finally
    Terminate;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  MyThr: TMyThread;
begin
  Edit1.Text := '';

  MyThr := TMyThread.Create(NotifyMainThread);
  try
    while not MyThr.Terminated do
      Application.HandleMessage;

    Edit1.Text := MyThr.StrResult;
  finally
    FreeAndNil(MyThr);
  end;

  ShowMessage('Завершенно');
end;

procedure TForm1.NotifyMainThread(Sender: TObject);
begin
  SendMessage(Handle, WM_NULL, 0, 0);
end;