Added a new "hide-with-mce" CSS class in Dynano; all elements which have it will be hidden when TinyMCE is activated, and re-shown when it is destroyed.
.mcePageBreak {display:block;border:0;width:100%;height:12px;border-top:1px dotted #ccc;margin-top:15px;background:#fff url(../img/pagebreak.gif) no-repeat center top;}