如何在miniPage中使用shinyFiles中的shinyDirButton？

install.packages("shiny")
install.packages("shinyFiles")

library(shiny)
library(shinyFiles)

ui <- shinyUI(
  fluidPage(
    miniPage(
      gadgetTitleBar("使用shinyFiles中的shinyDirButton"),
      miniContentPanel(
        shinyDirButton("dirButton", "选择目录", title = "选择一个目录")
      )
    )
  )
)

server <- shinyServer(function(input, output, session) {
  shinyDirChoose(input, "dirButton", roots = c(home = '~'), session = session)
})

shinyApp(ui, server)