Edit item in slot without breaking the defined action
Description
This addon is awesome but I came up with an idea.
It would be awesome if it was possible to edit an already defined item without removing the action of the previous item. This would make it easier to create dynamic GUIs without having to run a function every time you click the item to reopen the gui to the player.
Example:

Would be good to have. One thing you can do for now is to just update the item in the slot.
set slot 0 of the gui to dirt (something like that)
Would updating the item in the slot , using the way you suggest, not remove the action also?
I'm going try to make a pull request today to add this syntax, while I'm not bright with java as I've basically never made anything with it I believe this is something that isn't impossible for me to do.