always Off-hand

Displayed off-hand slot in block interaction GUI(example: Crafting Table)
This mode is like vanilla F key actions, but is visible slot.
This mod is only client

• Right Click is not supported
• Drag Click is not supported
• Wheel Click is not supported
• Q Key is not supported
• Double Click is not supported
• Slot Key is not supported
• Shift Click is not supported
• Hold another item and double click action is not supported
• TouchScreeen mode is not supported

• Implemented using
  • Change Main-hand <-> Off-hand
  • Click Main-hand
  • Change Off-hand <-> Main-hand
• The server receives packets like the above, so please be aware