TiddlyTalk "admins" (Boris, Jeremy, Mario, Mark, and myself) can post replies to a read-only category.
In principle, admins should always make sure that we post our replies to the GoogleGroup rather than the TiddlyTalk category so that we can be sure that the original poster will see the response even if they don't use TiddlyTalk.
However, since TiddlyTalk doesn't restrict posts by admins, it's easy to forget that the category is "read only" and so sometimes we post directly to TiddlyTalk by mistake.
-e