First you need to make the map smb3 styled World Map through the world map settings to use the inventory and after its done you can access the inventory with Alt run and you can also add items through the special events W.I.Add
OK, I think it works but what do I need to do to save items from levels in this inventory? I was playing in the editor when i discovered the "special events" folder in events. Does it have something to do with those "special events" ?