Other Syntax and Information - APickledWalrus/skript-gui GitHub Wiki
Has GUI Condition
This condition is whether the specified players have or don't have a GUI open. Syntax:
%players% (has|have) a gui [open]
%players% (doesn't|does not|do not|don't) have a gui [open]
Next GUI Slot Expression
This expression returns the character representing a GUI's next open slot. Syntax:
%guiinventorys%'[s] next gui slot[s]
[the] next gui slot[s] of %guiinventorys%
[the] next gui slot
Please note that the third pattern is only usable in GUI scopes (create, edit, make, open, close, etc.)
guiinventory
If you see this in patterns, it simply means the syntax wants a GUI.
Technical Note: The only reason it's called a "guiinventory" is because Skript does not like the name "gui"
Slot Types
armor - An armor slot in the player's inventory
container - A regular slot in the player's inventory (anything not covered by the other types)
crafting - A slot in the crafting input area
fuel - The fuel slot in a furnace inventory, or the ingredient slot in a brewing stand inventory
outside - A pseudo-slot representing the area outside the inventory window
quickbar - A slot in the hotbar
result - A result (or output) slot in a furnace or crafting inventory