This request arose from the discussion OPINION: Who thinks MAKING A POST on these forums is horrible. My comment on that thread was

If I am not logged in and I click on a link in my email, I am taken to that post. I can start typing a response but I can't post it because I am not logged in. At that point I have to copy all of the text I have entered to the clipboard, log in, then paste that text back into the text area. As far as I am concerned, since you can't post unless you are logged in then you should not be able to enter text.

My suggestion is that if a user is not logged in and looking at a thread then the text entry area should display as "You cannot post in this thread until you log in" or something equally as informative. Text entry should be disabled until the user logs in.