Especially while modeling tubtanks inside the legs of a jacket, it is usefull to make sure the location of the tank is correct. Also for reporting to client, the picture is usefull to fast understanding. The best way is to be able to display on the same picture the compartments within the body. For now on user has the choice to display external compartment OR internal compartments. The idea is to provide a mixed picture. Could be similar to the -color select option