A fake inventory is rendered in the background of the recipe book if it is rendered in front of the inventory because the window is not wide enough. This fake inventory is not rendering the items the player actually has in the respective inventory slots additionally if the player had an item picked up with they cursor when opening the recipe book the item is not displayed anymore but is still there which can be seen when clicking outside the GUI causing the item to be dropped.
- Place items in the first and last slot of your hotbar
- Open the recipe book
- Resize the window to have the recipe book being display above the inventory
→ The fake inventory in the background displays no items in the first and last hotbar slot