I haven't tried the new inventory system. But by default, they should try to support all methods of viewing the inventory... past and present.
Being a profressional game programmer, I'd have to agree with some of the previous posts that if the code is well written, unclicked the button to show all items is probably a 5 minute change. Especially since it worked that way before. The original code is probably still there, just commented out or something.
However, adding a new button to "show all" would definitely be more work.
