First, you must have at least 10 characters in the text of a message you are posting. That eliminates the "nm" option of giving a title and then putting a period in the text area.
Second, there is a difference between doing a reply to a specific response to a message(reply button at the bottom of the response), and using the reply button at the bottom of the thread. In responding to a specific reply, you will get the text of the message you are replying to inserted in your reply. Using the reply button at the bottom of the thread will give you a clear text area. It is like responding to a specific comment, and responding to the thread. I hope this makes sense....
Ken S., maybe you can make my muddy explanation clear.