Unwanted apparition of shiny output

[stla]

Hello,

I did a htmlwidget which renders some text in a blue div: findInFiles.

I noticed two strange issues with the Shiny output.

First, when I include the Shiny output in the UI without including the Shiny render in the server, the blue div permanently appears:

library(findInFiles)
library(shiny)

onKeyDown <- HTML(
  'function onKeyDown(event) {',
  '  var key = event.which || event.keyCode;',
  '  if(key === 13) {',
  '    Shiny.setInputValue(',
  '      "pattern", event.target.value, {priority: "event"}',
  '    );',
  '  }',
  '}'
)

ui <- fluidPage(
  tags$head(tags$script(onKeyDown)),
  br(),
  sidebarLayout(
    sidebarPanel(
      selectInput(
        "ext", "Extension",
        choices = c("R", "js", "css")
      ),
      tags$div(
        class = "form-group shiny-input-container",
        tags$label(
          class = "control-label",
          "Pattern"
        ),
        tags$input(
          type = "text",
          class = "form-control",
          onkeydown = "onKeyDown(event);",
          placeholder = "Press Enter when ready"
        )
      ),
      numericInput(
        "depth", "Depth (set -1 for unlimited depth)",
        value = 0, min = -1, step = 1
      ),
      checkboxInput(
        "wholeWord", "Whole word"
      ),
      checkboxInput(
        "ignoreCase", "Ignore case"
      )
    ),
    mainPanel(
      FIFOutput("results")
    )
  )
)


server <- function(input, output){

  # output[["results"]] <- renderFIF({
  #   req(input[["pattern"]])
  #   findInFiles(
  #     ext = isolate(input[["ext"]]),
  #     pattern = input[["pattern"]],
  #     depth = isolate(input[["depth"]]),
  #     wholeWord = isolate(input[["wholeWord"]]),
  #     ignoreCase = isolate(input[["ignoreCase"]])
  #   )
  # })

}

shinyApp(ui, server)

Secondly, if I include the Shiny render (by uncommenting in server above), the blue div appears as a flash (it appears during a small amount of time) while it is not rendered yet (input[["pattern"]] in the app above is NULL). I recorded a GIF of the app and I slowed it down:

Actually there's a third strange issue. Did you notice in the above GIF that the style of the selectInput changes when the blue div appears? Here is the image of this moment:

Cheers.

[stla]

Stupid of me... I've just (partially) understood. FIFOutput generates a div with the findInFiles class, so the first point is normal!

But why the change of style of the selectInput ?