Another, really problematic, bug with the new editor -- gets cut off! Answered
This was originally pointed out by Molten Boron in a comment embedded in another topic. It deserves it's own bug report. This bug causes substantial difficulty with actually being able to post comments.
When replying to a comment that is more than a few levels deep, the right margin of comments gets too close to the right sidebar. With the new editor, the text box itself gets CUT OFF, effectively "hidden behind" that right sidebar. This includes some of the formatting icons, as well as the POST and CANCEL buttons below the box. Also, the text you are typing gets hidden in the same way.
Obviously, this can make it impossible to successfully create a comment.