Under Settings/Discussion of the WordPress administration panel, I have made sure that "Enable threaded (nested) comments" has been selected (3 levels deep).
Under Avisio 1.1/WordPress 3.0.1, these nested comments do not work anymore (no plugins activated): comments all are appearing in a flat list. I'm in localhost for now and other themes with similar feature do work under same testing platform.
On aside: Background pattern missing on demo (another thread has been opened on this but no answer so far).
Thanks for a reply!