Directory Opus 10: How to go back to the old layout?

They window layout hasn't changed much between Opus 9 and Opus 10.

Do you mean the toolbars instead? There's already a FAQ for that; it's the 4th one in the list.

(If you've just reinstalled Windows and don't have a backup of your old Opus 9 configuration, I can send you the toolbars from mine.)