"Funny, that's the 10th time I've clicked the button [Open Inventory] and nothing happens?!" That's what it would sound like, if there were no one responsible for the functionality of the graphical user interface.

...hang on, there wouldn't even be any button to click...

As you already guessed, this entry is about the graphical user interface of Drakensang and the steps necessary to make some visible buttons that the player (you) can click on in the end. To explain how this process works, it would be best to demonstrate it with a simple ingame window, in this case the crafting window.