This is my first post at the forum, so I don’t know if this is the right place to do so. Anyhow, I apologize in advance.
As far as I’ve tried, there’s no functionality in the central button of the mouse in kicad(or is just the same as the left button). A great functionality for it could be to mirror selected parts, for example. Even cooler would be to be able to choose the functionality of that button, but that probably gets even more complex.