This is great point about a problem I've had in my early days of GUI programming. I'd take the author's suggestion a bit further: in terms of MVC a Controller

This is great point about a problem I've had in my early days of GUI programming. I'd take the author's suggestion a bit further: in terms of MVC a Controller should always call the appropriate function on its Model but the Model should check for an appropriate state before performing the requested action. Collecting state information in the Model would also make it easier for Views to adjust their appearance after a state change since there would only be one source of this information.