In the docs it says I can script the popup window which shows up on a desktop right-click and I should do it in step.rc.
However, I wonder where the script for the default popup is (it's not in my step.rc), because I already have a full functional popup. Does this have something to do with what theme one has installed?

Yes. Step.rc tells LS to go look in the current theme's theme.rc and in your own personal files. Theme.rc usually "includes" others setting files.

Depends whatr setting you're looking for. The files and folders contained in the popup are set in your personal popup.rc. Visual appearance, and everything else, is defined in one of your theme's setting files.

ah great, thanks.