Translate plotmath expressions

I have 2 issues using function ggplotly in R:

Question 1 What are the ways to keep R plotmath expressions while converting ggplot2 plots to plotly format using function ggplotly?

Now the expressions are converted to [object Object] as in this example below:

library(ggplot2)
library(plotly)

qplot(mpg, wt, data = mtcars) +
    ggtitle(expression(bar(x) == sum(frac(x[i], n), i==1, n)))

ggplotly()

Question 2

How to get rid of double labels in the legend of plotly graph and make them look like in ggplot2 graph? I.e. how to get 6 in stead of (6,6):

qplot(mpg, wt, data = mtcars, colour = as.factor(cyl), fill = as.factor(cyl))

ggplotly()

Inizia riproducendo entrambi gli esempi segnalati con ggplot2 e ggplotly: il titolo plotmath diventa [object Object] e la legenda mostra valori duplicati come (6,6). Traccia il modo in cui ggplotly converte le espressioni plotmath e le scale combinate colour/fill, quindi verifica che le espressioni vengano renderizzate correttamente e che le voci della legenda corrispondano al risultato di ggplot2.