What is happening:
The characters have 36 inventory slots but with only 35 visible slots, and you can see whatever is on the 36th one when trading.
What should be happening:
All 36 slots should be visible, or keep it at 35 without being able to get a 36th item.
Steps to reproduce the issue:
Get your inventory full (the 35 visible slots) and then get another item, either by buying it, picking it, or receiving it from trading and then trade with a player to see that extra item.
Game client version:
Windows 7 Ultimate 32-bit SP1
Win 8.1 64bit
Windows 10 64 bit
Extra items in the video: 10 pears, iron legs and potion bags.