Yes, that is correct.
When code was moved to Irrlicht 1.4, only compiler errors were fixed.
In order to make it work, you have to use 1.4 OnEvent functions for GUIWindow, and CIcon. I There were some changes in event handling, so you have to do it like that for it to work properly.
I made those changes and succeded to make code work fine, I can post changes later, but during code exploration I relized this GUI component was pretty awkwardly coded. There is two new classes CSlotWindow and that BringUpButton wich don't do anything different then regular component (CSlotWindow creates slotArray and returns it but its not even member component of CSlotWindow, and BringUpButton shows/hides window wich any regular button can do - no need for special class I think).
my favorite is
Dragged = true*Movable;
Anyhow, I think This inventory should be one GUI class that can be added to window like any other button or list or text. It should have addItem and couple of more functions and thats about it. If I make something like that usable, I'll post it.