Hi Didier, Joe regularly updates the version of CKeditor that's shipped with mojoPortal, and often the code running on mojoPortal and the demo site is newer than the most recent official release.
I'm not sure which version of CKeditor shipped with 2.3.9.7, but I can confirm that in the latest code it's using CKeditor 4.11. If you look in your web.config file, you'll see an entry like this:
<add key="CKEditor:BasePath" value="~/ClientScript/ckeditor403/" />
Check under ClientScript and you can see what versions of CKeditor are in your installation. You can then change the CKEditor to any installed version by modifying the above web.config key, if desired.
I hope that helps,
Jamie