Forum

Willem,

I haven't delved very deeply into this one, but it looks like the group id is set at the level of the discussion rather than on individual posts.

If a teacher creates a discussion for Group A, then the whole discussion is a 'Group A' discussion and members of that group can see and reply to all posts.

However, if a teacher creates a discussion for all participants, the group id for the discussion is -1, meaning everyone can see it - it's essentially a no-groups discussion within a separate group forum. If group members were allowed to reply to posts within such a discussion, the replies would also be seen by everyone and it would no longer be a separate group forum!

The creation of a discussion for all participants within a grouped forum is really just intended, I think, to be used for announcements.

Hope that helps!
-Ann