This page lets you configure commands that run when you double-click empty space in the file display. You can configure commands for both left and middle button double-click, optionally with the Ctrl, Shift or Alt keys held down (so up to eight commands in total).
Middle button commands can also be set to trigger on single-click using the dropdown menu.
You can enter any Opus command line into the fields. For example, Go UP BACK to make double-click automatically go back to the parent folder. If you want to run a more complex multi-line command, you can do this by creating a user command.