In any lister/viewer that I use in Directory Opus, the left-side margin does not exist. That means whatever folders are furthers to the left, have no space to their left. Thus, the lister/viewer can be difficult to work with. Why am I experiencing this problem? What setting do I need to tweak to get some margin space?
Assuming you're using Full-Row Selection, try the Name Column mode instead. It's a good balance between name-only and full-row, since it gives plenty of space to select things but also plenty of space to de-select them.