Plotly plot is pushed out of bounds in flexdashboard

[kendavidn]

I am having trouble getting my plotly plot to fit in its flexdashboard container. The bottom gets cut off.

Consider the following reprex:

    ---
    title: "Plotly Flexdashboard Conflict"
    output: 
      flexdashboard::flex_dashboard:
          source_code: embed
    
    ---
    
    Column
    ---
    
    ### In this tab, the plot is pushed out of bonds by the selectize items.
    
    ```{r}
    library(tidyverse)
    library(plotly)
    library(gapminder)
    library(flexdashboard)
    
    gapminder_highlighted <- 
      highlight_key(gapminder[1:408,], ~country, "Select a country")
    
    gapminder_ggplot <- 
      gapminder_highlighted %>% 
      ggplot(aes(x = year, y = lifeExp, group = country), alpha = 0.2) + 
      geom_line()
      
    gapminder_plotly <- ggplotly(gapminder_ggplot)
    
    highlight(gapminder_plotly, dynamic = T, selectize = T, persistent = T)
     
    ```
     
    ### Without selectize, all is well. The x axis is visible.
    
    ```{r}
    gapminder_plotly
    ```
    
    Column
    ---
    
    ### When plots overflow, flexdashboard is meant to add a scrollbar. E.g.
    
    ```{r}
    plot(cars)
    plot(nhtemp)
    plot(cars)
    plot(nhtemp)
    ```
    
    ### Although this does not actually work for all elements. E.g. Text generated from code chunks fails to trigger slider     addition: 
    
    ```{r}
    cat( rep("Flex is not responsive to text overflow here.           ", 100) )
    print("This line is hidden")
    ```
    

Output is on Rpubs here so you can have a look: RPubs - Plotly Flexdashboard Conflict

The first gapminder plot is pushed out of bounds by the selectize items. And flexdashboard doesn't trigger the addition of a vertical scrollbar like it should.