You can actually do this with normal Skript if you know the slot index

[Ruk789]

How can I obtain the icon with ID x in the GUI? And display the lore of each icon

[APickledWalrus]

Hmm I don't believe there is a direct way to do this. You could read the characters of the shape of the GUI if you need to dynamically determine what indexes are valid

[Ruk789]

How can I obtain slots for ID? By the way, when will version 1.4 be released?

[APickledWalrus]

You would have to create your own solution. Something like

set {_chars::*} to shape of {_gui} split at ""
loop {_chara::*}:
  if loop-value is "x":
    set {_item} to slot {_index} of {_gui}
  add 1 to {_index}

also, I unfortunately don't have much to share regarding 1.4 at the moment (not that there has been much progress)

[Ruk789]

Thank you for your answer! But I am setting the gui slot to a removable item. Please note that the item is not an air and I cannot replace the removable item by dragging the items in my backpack. Is this a bug?

[APickledWalrus]

You should be allowed to do an inventory drag as long as all of the slots are removable. It could that something is wrong if it's not letting you.

[Ruk789]

create a gui with virtual chest inventory with 3 rows named "":

make gui 10 with removable lever:
			
    send " OK! "

open last gui to player

This does not allow for dragging items for replacement, but it will also prompt OK! This information