I guess the same answer is true.
I think it's better to have the thumbs in the pockets rather than having weird stress gestures, closed body language (crossed arms) or the hands in the pockets.
The hands are not fully visible, but they are ready to move if needed. So it's somewhere between high confidence and low confidence. That said, I know many people for who it is the default stance and therefore it doesn't really mean anything.
It mainly depends on the context I think. Look at the shoulders/elbows/head. It the person is shrinking it's low confidence, if the person is expending it's more a relaxed body language.