Actually, she would fall forward to her left. Notice that the majority of her mass is to the front and left of her center of gravity? That lifted thigh would pull her over since, as you can see here, she's not leaning at an angle at all, but nearly perfectly erect. The belly button rule is good for figures that are supposed to be standing on their own, but she's supposed to be borrowing a point of contact from the wall and leaning, which would throw her center of balance to the rear. I hope this helps some.