Node editing arrows

I have made myself simple node editor, but it lacks important function - an arrows.
So it is often hard to find what is parented to what.

I want to draw arrows between UIElements. Is it possible to draw on GUI?
Is there some helper I could use?

Lumak created some elements that may be helpful to go through. Hope you can find it useful here: Perhaps some useful UI components

I was very lazy and implemented everything ad-hock using arrow sprite drawn in Krita