The first thing we're going to look at is using the shinyBS package to add pop-up windows and tooltips. There is more on the functionality of the shinyBS package present at cran.r-project.org/web/packages/shinyBS/shinyBS.pdf. If you haven't installed already, install shinyBS with install.packages("shinyBS").

The server.R file is very similar to the version we encountered in Chapter 2, Building Your First Application, except the map that has been removed (this will be added back in later on in the chapter), and there are a couple of more functions to power the new UI elements.

The first changes are visible at the top of server.R; we are using the shinyBS package:

...[load packages from original application]...
library(shinyBS)

Also, shinyServer() takes a session argument:

shinyServer(function(input, output, session){

We saw the use of the session argument in Chapter 3, Building Your Own Web Pages with Shiny; in this case, it will be used for two purposes...