CustomSVGSeries and onNearestX on version 1.10.2

[fabienjuif]

I think this is a regression from 1.10.2 over 1.10.1.

onNearestX isn't triggered anymore on version 1.10.2.
Maybe this is related to the ref thing because I use stateless component.

I just try to revert back to 1.10.1 and it works.

[fabienjuif]

I don't know why the ref thing would break onNearestX, but nevermind:

• Related PR Check if stateless before adding ref #868
• Related issue with the last comment you should address IMO: Stateless function components cannot be given refs. Attempts to access this ref will fail #861 (comment)

[markov00]

I think it breaks the onNearestX is called from the onParentMouseMove events passed by the XYPlot mouse handler _mouseMoveHandler. The onParentMouseMove is triggered only to components which ref is saved into the xyplot has the series-index .
If my comments and solutions are right, this means that we are no more saving the series refs into the xyplot avoiding any calls to onNearestX etc calls.

[mcnuttandrew]

I would accept a PR that adds a fix and regression test against this behaviour