Stack of 20 logs in a slot.
Player can hold 10 logs.
Player picks up the stack of logs.
10 logs are in hand, looks like 10 are left in the slot
Bug A:
Drop the 10 in hand into another slot.
Click on the 10 left, and they disappear.
Bug B:
Drop the 10 back onto the stack.
10 are still in hand, and the slot shows 20