I agree with Eric about the problem of not being able to read the previous message while composing a reply.

However, sometimes it's useful to refer to information in several of the messages in the thread, so the method I use to get round the problem is this:

Display the message at the end of the thread, or the specific one you want to reply to. Then open up a new tab so that you have 2 identical versions. Use one to compose a response, and the other to move between messages in the thread. You can also have the opportunity to refresh the page and make sure that noone else has already posted a reply similar to the masterpiece you're in the middle of composing.

Jean C