You currently can't grab items from a furnace, brewing stand, or chest if you're holding that same item in your hand, even if it would make sense to merge the two stacks together! This should be fixed, and have the following behavior:

• Furnace and brewing input slots should have the item in the hand merged into the slot
• The furnace output slot should have the item in the slot merged into the hand
• Chests should merge items into the slot

Closed by 0339c4e