This is not fixed in 1.0.1.
However, it has a fairly obscure recreation path. I'm in the middle of documenting a few things concerning the Node Tree, and created a forum that way. I run a seocnd browser where I am logged in as a regular user. I created a thread with that regular user, and posted it. Then in the first browser, I set the node to not allow new messages.
Switched back to the second browser, where the reply button then still is visible. Tried to post a reply, and then see the above behaviour. If I totally refresh my browser, the forum will correctly state I have insufficient priviledges to post, rather than offering a reply button.
To confirm, use two browsers, and ensure the setting is set to be open for posting when you load the regular user window. Once done, CTRL + F5 to flush browser cache. Reply button will become visible. Switch back to admin window, and turn off option to allow posting.
Switch back to regular user browser, and attempt to reply.
