roippi put a collapsable panel into the chat GUI to tell you when you are in away mode. I suspect that something similar could be done to the sidepane to optionally display lines without gaps when they are absent.
(The existence of that widget was news to me; I remember wishing for something like that when I put th Container line in the Gear Changer; I wanted it to appear if you owned a Container and disappear otherwise. When it turned into the Back slot, there was no need for that, since back items are easy to get...)