If it worked for you, it's because you are using a different script, since you aren't setting the grid list item data later used.
for u,i in ipairs (skins) do
local row = guiGridListAddRow (GUIEditor_Grid[1])
guiGridListSetItemText (GUIEditor_Grid[1], row, 1, tostring(i[1]), false, false)
guiGridListSetItemText (GUIEditor_Grid[1], row, 1, tostring(i[2]))
end
Should be:
for _, i in ipairs (skins) do
local row = guiGridListAddRow (GUIEditor_Grid[1])
guiGridListSetItemText (GUIEditor_Grid[1], row, 1, tostring(i[1]), false, false)
guiGridListSetItemData (GUIEditor_Grid[1], row, 1, tostring(i[2]))
end