If you have upgraded to FF 23 and suddenly your CKEditor is not working (in admin->catalog->categories/products), take heart: it's a one line fix to get it back again. Edit

<your renamed admin>/includes/ckeditor.php

and change the inclusion of jsapi to not use a protocol, i.e.

<script type="text/javascript" src="//www.google.com/jsapi"></script>

instead of
<script type="text/javascript" src="http://www.google.com/jsapi"></script>

and you should be all set. You will NOT see this issue in FF 22 and prior, only FF23 (and perhaps higher).


NOTE: The latest CKEditor package in the ZC Plugins area already has this change in it.