Several enterprising users have noticed that you can use the new Jobs tab to run Shiny applications in the background, using a multi-step process:

1. Create a host script that runs the application
2. Run the host script as a local job in the Jobs tab
3. Copy the URL from the script's output and open it in the Viewer (or an external browser with rstudoapi::translateLocalURL)

This is a nifty trick and popular enough that we could consider offering a gesture that embraces and simplifies this workflow, for example by having a checkbox in the Run App dropdown that says Run as Job. In this mode, the Shiny app would run as a background job in the Jobs tab, and you could continue to work as usual while interacting with the Shiny application. Of course, you wouldn't get debugging and would possibly lose other features (for example the run/reload/stop buttons have some edge cases to consider) but would be very helpful for some use cases.