I guess lines and arrows are treated as ‘graphics’.
It would be really nice if you could use them a bit more ‘freely’.
No matter what I try, sometimes I move one arrow and another one is affected.
Or I shut down my session with all arrows being on the right position, open it again and some of the arrows are ‘de-placed’.
Something like a switch off for ‘avoid collision’ would be of much help, but I guess this is very difficult to realize for graphics.