You will see this window during exporting file list to a web page (wList main menu: File → Export to HTML Web Page or Ctrl+H).
If you change any settings in this window, you should manually generate new HTML web page by pressing "Generate" button.
When you list from more than one location, "Relative Path" is disabled. Example: when you list from standard location "<Desktop> | <My Documents>", than "Full Path" option will be the only choice.