In a similar way that you can with the active layer, you can quickly change the active class. Hold down the control key (Windows) or the command key (Macintosh) and use the left and right arrows to quickly change your active class. one way that you can use this to is to find objects on a particular class. Turn all the classes off except for the None class. Then use this technique to quickly scroll through all the classes looking for the information that you want.