Event "plotly_legendclick" returns unreasonable results for member $visible

[dieter-wilhelm]

Brief description of the problem:

1. For a first click on a(ny) legend entry there is no member $visible at all, even though the markers are not visible.
2. For even numbers of clicks on legend entries $visible is "legendonly" (markers are shown).
3. For odd numbers of clicks $visible is TRUE (respective markers are not shown).

Please consider as reprex: https://github.com/ropensci/plotly/blob/master/inst/examples/shiny/event_data_legends/app.R

[davidrsch]

Hello, is anyone looking at this issue?