Get refs from scrollable elements & prevent memory leaks

[alioshr]

There should be a way of getting the refs of the scrollable elements used within the ScrollPanel elements.

I need to investigate why it is not possible, but I have tried with callbacks and regular refs. I assume that this is being kidnappted internally, to make the feature work.

Another thing that I have noticed is that after a while the scroll sync get chunky. I guess that is a certain point of time both elements start listening to each other at the same time, which makes the scroll chunky.

I will post more here during this week to enhance my findings, as I will need to reproduce this on public code.

[wbolduc]

This exact issue causes problems when you're using other scroll related libraries like react-virtual to visualize items on your synced list