Right now it isn't possible. I will put this variant in next template. If you need quick fix, you can inspect class for sidebar when you resize your browser window, and put this class by default. But you will also need to force classes on subelements in menu too. Or wait for next release ;-)
How to make that sidebar(menu) was […]
I have uploaded new version. You can download it from wrapbootstrap. I've added option to close menu by default. Hope it will help you.