Use uiOutput/renderUI to implement a "settings" page
I need a way for users to change global settings, but don't want to dedicate valuable real estate on the web page for that purpose. A pop-up window would do the trick but I haven't found out how to do pop-up windows in shiny.
This solution is for a pageWithSidebar layout. It replaces the mainPanel content with a "Settings Page" accepting text input from the user and holding an actionButton to re-display the "Main Page" when clicked. The user input carries over and replaces the original content on the Main Page.