Allow on/off to accept multiple values

Code:

library(plotly)
library(crosstalk)
D <- SharedData$new(iris, key = ~Species) 
scatter <- ggplot(data=D, aes(x = Sepal.Length, y = Sepal.Width)) 
p <- scatter + geom_point(aes(color=Species, shape=Species)) +
  xlab("Sepal Length") +  ylab("Sepal Width") +
  ggtitle("Sepal Length-Width")
highlight(ggplotly(p), on = "plotly_selected",  off = 'plotly_deselect')

Step 1, I select the red group:

Step 2, I click somewhere else in the plot: (here is the BUG, it acts the same as off = 'plotly_doubleclick' )

Using double click releases the fading.

Start by running the supplied R example with highlight(ggplotly(p), on = "plotly_selected", off = "plotly_deselect") and compare it with the double-click behavior described. Trace how highlight handles the on and off arguments; done means multiple values are accepted and clicking elsewhere no longer behaves like plotly_doubleclick.