How to open a downloadHandler downloaded file in a NEW tab in the user's browser?

Question

I am learning Shinyapps.io and shiny. I hope to use it for teaching. I would like to run some computations, generate from Rmd an html file and show the user that html file in user's Browser in a NEW tab. I can do this on my Windows 7 with RStudio using Pander's openFileInOS. I can show this html file in shiny tab using Render .... but not in a NEW tab in the Browser. How do I do this?

# File Downloader. Needs report.rmd in the current directory to make it work
# https://shiny.rstudio.com/articles/generating-reports.html  Winston Chang, July 2016

library(shiny)
library(here)
here::here()

  ui = fluidPage(
    sliderInput("slider", "Slider", 1, 100, 50),
    downloadButton("report", "Generate report")
  )


  server = function(input, output) {
    output$report <- downloadHandler(
      # For PDF output, change this to "report.pdf"
      filename = "report.html",
      content = function(file) {
        # Copy the report file to a temporary directory before processing it, in
        # case we don't have write permissions to the current working dir (which
        # can happen when deployed).
        tempReport <- file.path(tempdir(), "report.Rmd")
        file.copy("report.Rmd", tempReport, overwrite = TRUE)

        # Set up parameters to pass to Rmd document
        params <- list(n = input$slider)

        # Knit the document, passing in the `params` list, and eval it in a
        # child of the global environment (this isolates the code in the document
        # from the code in this app).
        rmarkdown::render(tempReport, output_file = file,
                          params = params,
                          envir = new.env(parent = globalenv()) 

                        ) # downloads report.html

# ???        
# How do I open the report.html file in a NEW tab in Browser, not a tab within Shiny?    
#                          
       # )
      } # content ends
    ) # downloadHandler ends
  } # server ends

  shinyApp(ui = ui, server = server)

any rmd file. here is report.rmd file code

---
title: "Dummy Report"
author: "John Doe "
date: "April 13, 2019"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see http://rmarkdown.rstudio.com.

When you click the Knit button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

summary(cars)

Including Plots

You can also embed plots, for example:

plot(pressure)

Note that the echo = FALSE parameter was added to the code chunk to prevent printing of the R code that generated the plot.