It seems we use LDCad in a similar way. Yes, tabs would be even more comfortable but a submenu under "Model->change current model" is OK for me as well, thanks to Roland's system of menu: one can "pin" the submenu on the screen for faster access. Not so comfortable as tabs but doable.
The main point is the equivalence: MPD file == session.
The main point is the equivalence: MPD file == session.