pointNumber passed to Plotly.Fx.Hover() is not used for box plots

When attempting to build off of the Coupled Hover Events example, I've found that box plots don't appear to make use of the pointNumber property of evt. I did find a workaround that uses xval and yval, but, in addition to being a bit more verbose, it can cause the wrong point to highlight if several are close / overlapping, so some way to specify particular points still seems useful.

https://codepen.io/cszucko/pen/gONaZqd

リンクされた「Coupled Hover Events」例とCodePenを使用して問題を再現し、box plotでのPlotly.Fx.Hover()に焦点を当てます。pointNumberの動作をxval/yvalの回避策と比較します。pointNumberが、点が重なっている場合も含め、指定されたbox plotの点を確実にハイライトできれば完了です。