rHighcharts issue : bar chart

[ochees]

Hello,

I post an issue concerning rcharts (highchart) library and shinydashboard in rCharts repository. I need this kind of visualisation and I didn't find a solution. Here, the problem :

This is an example of application mixing shinydashboard and Highchart. There are two problems :
-first, with an initial input of 50, the app doesn't display the plot. The user must click on the label "Series 1" to load the plot. Not intuitive.
-with a variable numeric input, the plot is totally blank and doesn't response anymore to the input user.
The problem is the same when using an action button and isolate function or not.

library(shiny)
library(shinydashboard)
library(rCharts)

ui <- dashboardPage(
  dashboardHeader(title = "Basic dashboard"),
  dashboardSidebar(),
  dashboardBody(
    # Boxes need to be put in a row (or column)
    fluidRow(
      box(title = "Slider", status = "primary",sliderInput("slider", "Slider input:", 1, 100, 50)),
      box(title = "Load", status = "primary",actionButton("actionButton","Load",icon=icon("refresh"))),
      box(title = "Plot", status = "primary",showOutput("chart", "highcharts"))
      )
    )
  )
)

server <- function(input, output) {
output$chart <- renderChart2({
input$actionButton
a <- Highcharts$new()
a$chart(width=500,height=500)
a$series(data = list(
list(x = 0, y = isolate(input$slider), capital = "Stockholm", country = "Sweden"),
list(x = 1, y = isolate(input$slider)+10, capital = "Copenhagen", country = "Denmark"),
list(x = 2, y = isolate(input$slider)+20, capital = "Oslo", country = "Norway")
), type = "bar"
)
a$xAxis(categories = c("Sweden", "Denmark", "Norway"))
a$addParams(dom = "chart")
return(a)
})
}
shinyApp(ui, server)

Maybe it's a bad interaction between shinydashboard and rCharts ? this app works well using a classic shiny structure or a type of graph "column".

Besides, i would know if it's possible to draw in this kind of graph a vertical (for a bar chart) or horizontal (column chart), parallel to x axis, as a limit ? I saw something with the plotLines command in highcharts js. In the same way, is it possible to add text on chart with R ?

Thanks a lot,