用sendmessage 发送消息，但onmessage还是能获取到，求助~

Question

procedure TForm1.ApplicationEvents1Message(var Msg: tagMSG; var Handled: Boolean);
begin
  if Msg.message = WM_LBUTTONDOWN then
  begin
//    mmo1.Lines.Add('OnMessage');
    ShowMessage('OnMessage');
    Handled := True;
  end;
end;procedure TForm1.btn1Click(Sender: TObject);
begin
  SendMessage(Self.Handle, WM_LBUTTONDOWN, 0, 0);
//  Perform(WM_LBUTTONDOWN, 0, 0);
//  PostMessage(Self.Handle, WM_LBUTTONDOWN, 0, 0);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  mmo1.Clear;
end;

Answer 1

点击后还是会  ShowMessage('OnMessage');   请问怎么回事啊？

Answer 2

看的万一大大的教程用sendmessage和perform 发送消息，application的onmessage是不会有反映的 ，可是我这却有反映