Delphi Thread sendmessage

type
  TThreadWithMsg = class(TThread)
  private
    { Private declarations }
    procedure WMUser(var Msg: TWMNoParams); message WM_USER;
  protected
    procedure Execute; override;
  end;

{ TThreadWithMsg }
procedure TThreadWithMsg.Execute;
var
  Msg: TMsg;
  DMsg: TMessage;
begin
  PeekMessage(Msg,0,0,0,PM_NOREMOVE); // Create Message Queue
  while not Terminated do begin
     Sleep(10); // don't eat CPU cycles
     if PeekMessage(Msg,0,0,0,PM_REMOVE) then begin
       DMsg.Msg:=Msg.message;
       DMsg.wParam:=Msg.wParam;
       DMsg.lParam:=Msg.lParam;
       DMsg.Result:=0;
       Dispatch(DMsg);
     end;
  end;
end;

procedure TThreadWithMsg.WMUser(var Msg: TWMNoParams);
begin
  Beep(440,100);
end;

{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
begin
  MyThread:=TThreadWithMsg.Create(False);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  MyThread.Terminate;
  MyThread.WaitFor;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  PostThreadMessage(MyThread.ThreadID,WM_USER,0,0);
end;