I believe that not only is the order intended to prevent actions that would harm the value of the marital property, but also to prevent use of community funds to increase the value of property that will be awarded to one party in the end. If they've already had an appraisal in order to determine the value, then one party spends community funds to increase that value, but the increase is never addressed in the division of property, then that party was unfairly compensated.
That said, while painting a room is, in a strict sense, a violation, it probably doesn't rise to the level of cheating the other party out of common property. I suppose it depends exactly how it's being done; is this a professional paint crew, moving furniture out, using a high-end finish, and making other alterations such as molding? That could cost several thousand dollars. Or did the wife buy a can of paint and a roller?