窗口显示于parent控件上（用到了ManualDock函数）

procedure TForm1.btn1Click(Sender: TObject);
begin
  with TForm2.Create(self) do
  begin
    ManualDock(self);

    WindowState := wsMaximized;
    Align := alClient;

    Show;
  end;
end;

http://blog.csdn.net/shuaihj/article/details/6371904