Code (Text):

1. on inventory click:
2.     if type of event-inventory is creative inventory:
3.         cancel event
4.         send "No."

Might work, didnt test it

 

the proper syntax for that would not be event-inventory, try player's current inventory
when you want to create a GUI with skript, at least for how I do it, I do:

Code (Text):

1. open chest inventory with 3 rows named "Chest" to player
2. set slot 11 of player's current inventory to feather named "&fFeather"

maybe when you use current inventory it will work.(Edit.)

 

OK, I found another forum that had the same question. https://forums.skunity.com/threads/creative-inventory.16051/
It looks like the used skript reflect to solve it.