The latest bug is fixed. The file is attached in my original post - I discovered that if you edit posts under IE, of all things, you get the advanced editor and can change the attached files. All others reading this thread should get the fix from the original post.

Edit: My bad (at least partly). It turns out that if you click "edit post", then Go Advanced, you don't get the advanced editor. But if you double-click on edit post, it goes straight to advanced editor on all platforms.