Right now, when you shift click an item while accessing the inventory of a storage container, it transfers the entire stack.
Let's say that theses conditions are true:
- Inventory of that container has a stack in every single slot.
- Container has a stack of items that isn't full
- You have some of those items
Let's say that you shift click. Nothing happens. Instead, I think that items should be transfered up to the stack's maximum possible count, leaving anything that is above in your inventory, or that of the container you are transfering from.