Easily able to compare a previous version to the new version. And make the resolved issues still appear when reviewing.

Right now for review, the person has to click the on the previous proof link (the one they marked up with their comment) and the link for the new proof that was created and toggle back and forth between windows to make sure the changes they requested were made. Also, if they can't remember what changes they requested, any change that I mark as "resolved" disappears and you have to click the filter icon and click "resolved" to get them to pop back up. This is a headache when you have to explain to every client how to get the marked up comments back.