In a context where you want to grab a chunk of information from the user a very light weight "open window, grab data, close window" is useful. In that context you don't want to go hunting for the $main that you may, or may not, have used before.

I use this trick in apps that are essentially command line (or run from desktop short cuts) that sometimes need a little more info. It lets me write one utility that I can drag and drop onto, have snoop stuff out of the clipboard, or (if the other strategies fail) ask for the required info.