my_inventory_menu:
    type: inventory
    title: My Inventory Menu
    size: 27 
    slots:
    - "[] [] [] [] [] [] [] [] []"
    - "[] [] [] [i@my_inventory_menu_slot12] [] [] [] [] []"
    - "[] [] [] [] [] [] [] [] []"

my_inventory_menu_slot12:
    type: item
    material: red_wool
    display name: Diamond


inventorychange_command:
    type: command
    debug: false
    name: inventorychange
    usage: /inventorychange
    description: Makes an NPC execute commands!
    script:
        - narrate "Opening GUI"
        - inventory open d:in@my_inventory_menu
        my_inventory_menu_handler:
            events:
                on player clicks in my_inventory_menu:
                    - determine cancelled
                on player drags in my_inventory_menu:
                    - determine cancelled
                on player clicks my_inventory_menu_slot12 in my_inventory_menu:
                    - narrate "Hey"