The current inventory screen isn't much:
That thing that looks like a rock is actually a treasure chest. And it has stacks of wood in it. Stuff like that happens, ya know? At least this one isn't floating out in the water like a whole bunch of the other test treasure chests I spawned to see if the system works.
I did design the system to allow any number of inventories of any size, though, so if I choose to implement multiple bags it shouldn't be a problem. I am kind of re-thinking my previous stance on item stacks, though. It kind of depends on how I structure my resource supply chain. If it turns out the player has to process and re-process resources a lot I might let them stack. I'll have to see how it pans out once I get a little further along with the crafting system.
Battle axe? Not stackable. Wood? Up to 10 in a stack. Herbs? Up to 20. Arrows? 15 to a stack. (for example)
If you take this route, a few tips to make things less annoying: Always show the number of items in a stack right next to the item. Don't force the user to click on the item to see them amount in the stack. Don't show the number '1' on a stack if that item isn't stackable. Also, when a stack is 'full' color the number in the stack a different color (like yellow) to let the user visually know that it is full.