No dashed or dotted grid lines with ggplotly

It seems that ggplotly cannot handle dashed or dotted grid lines. They always default to solid grid lines.

No matter whether I am specifying the general option panel.grid or a specific one like panel.grid.major.y, they always become solid with ggplotly.

library(ggplot2)
library(plotly)

# Dotted and dashed grid lines appear with ggplot2
p <- ggplot(mtcars, aes(disp, mpg)) +
  geom_point() +
  theme(panel.grid = element_line(colour = "red",
                                  linetype = "dotted")) # same issue if "dashed"

p

# However, with ggplotly they become solid
ggplotly(p)

Start by running the R example from the issue with ggplot2 and ggplotly, then trace how panel.grid and panel.grid.major.y settings are converted. Done means dashed and dotted grid lines remain dashed or dotted in the ggplotly output, matching the original ggplot2 plot.