According to this page: http://ckeditor.com/demo#div the editor by default uses an iframe. By changing this to a div container the styles used are inherited from the page.

Does anyone know how to apply this change?

If the main aim is to use page common styles — you can done it with iframe right from the box (since 0.9.15).

Here are the manual:

1. add to the and of your theme RC file (`theme.rc.php`):

global $ckeditor_css_to_load;
$ckeditor_css_to_load = array(
    $cfg['themes_dir'].'/'.$usr['theme'].'/css/bootstrap.css',
    $cfg['themes_dir'].'/'.$usr['theme'].'/css/bootstrap-theme.css'
);

edit `css/bootstrap.*` path to point to resources needed for loading in iframe.

It's more secure as you can use special styles for you CKeditor.

http://stackoverflow.com/questions/15031840/ckeditor-div-based-editor

Does anyone know how to apply this change?

More generally, is it possible to further customise our ckeditors to include plugins/addons such as the equation editor?

I've figured out my second question. Simply:

1. Add the plugin to the plugins/ckeditor/lib/plugins folder.
2. Modify the line: "config.extraPlugins = 'eqneditor,more,oembed,syntaxhighlight';" in plugins/ckeditor/lib/config.js.
3. Add the button 'EqnEditor' somewhere in the full toolbar.