While using any GUI, including just your inventory, and having the Tab button set as a hotkey for your hot bar, the button does not function correctly. If you, for example, have the "1" button set as your hotkey for your first hot bar slot, and you press "1" while your cursor is hovering over an item in a GUI, that item will be transferred to your first hot bar slot. However, this entire function does not work at all when "Tab" is set to be a hotkey for a hot bar slot. If the player tries to quickly transfer an item using "Tab" as a hotkey slot, the item does not move, forcing the player to manually drag the item to the slot they have "Tab" bound to.