With the new third generation editor, programming did away with the Button link option that allowed you to customize the email reponse with pre-filled subject and content lines. It was probably the best feature CC had and now and it has been dumbed down for some reasone. Then to make matters worse, the source code feature is now gone from the button system so you cant even make embeded changes. I guess the programmers think the users are stupid and cant use HTML.
Unfortunately there are a lot of good things in the third generation editor so I hope this option is returned.