CKEditor does not work with Rails 3

Hello there.

Sad but true : CKEditor does not work in Rails 3 projects. It's kinda strange, but I'm no expert, so all I can tell is that if CKEditor effectivly seems to work anywhere else, it won't work with ANY Rails 3 project (I didn't tried without the jquery gem, but it's included by default so...).

Even in a completly naked Rails 3 project, and without using Rails automatic javascript compilation, it just won't work. What's up with that ?

Uncaught TypeError: Property 'focus' of object [object DOMWindow] is not a function
e.extend.focus
j.add.init.C.on.C.addMode.focus
a.editor.focus
a.command.exec
e.extend.execCommand
k.button.e.extend.click
k.button.render.t.execute
a.tools.addFunction
a.tools.callFunction
(anonymous function)
onclick

HOW TO REPRODUCE :
-> Create a Rails project. There's no change to be made in the configuration (except maybe the routes).
-> Create a view with a div containing HTML.
-> Put the ckeditor source in /app/assets/javascript
-> Add this piece of Javascript in the view :

<script type="text/javascript">
$(document).ready(function() {
  CKEDITOR.replace('the-id');
});
</script>

Assuming the div you created has 'the-id' for id.

I assume you know how to render the view : just watch the result, open the console, and try using, for instance, the "bold" button of the CKEditor.
You should notice the exception I mentionned above.

Tested using Rails 3.1.0.