What does the "scroll" box after a node mean in DOM inspector?

Question

I noticed while inspecting a document that at some point, a square box with scroll appears next to it.

Unlike event box, clicking on it doesn't trigger anything. I first thought it just means a scroll event is attached to the node element, but as there are many scroll related events under the event box, it must be something else.

What does the scroll box after a node mean exactly?

Answer 1

This scroll marker means that the element is a scroll container and its content overflows its viewport. There is a short tooltip indicating that:

Because there was no documentation for that on MDN, I have now created a table describing all possible markers.