If you start the thread, you can edit it at any time. the ‘Edit’ button covers part of the title and is hard to see.
If you’re replying to post, you can only edit it for a couple minutes. Lame.
If you click the edit button obscured by the title, then change the post id to another one of your own posts, you can edit it for as long as required.. I edited a reply 24 hours old using that.
edit: I have removed the link, sorry.
