Mhm, I see the differences, but I have no idea how to add something like this, as there isn't a nicely defined 'category' for this, such as, say, civics, bonuses, processes (which is what seems to be used).
I saw something about adding new widgets, but eh, I know nothing about this, and considering I know which technologies give me what when it comes to Settlers, I suppose I can do without icons on the tech tree in this case.
Thank you anyway, though!