WARNING: This still doesn't protect you from losing your posts if your session has become invalid before you click on Submit, however, so it's still a good idea to copy your post to the clipboard before posting just to be sure!
By the way: The timeout for forum sessions is 2 hours, so your session shouldn't actually become invalid because of a timeout. I'm not actually sure what causes this occasional problem. It may be a browser issue, possibly security settings, because some people seem to suffer from it more than others.
