I followed the process in this question and everything works, but I wanted to see the order in my displayed page.
I updated My controller with this:
$this->crud->orderBy('lft');
But it doesn't seem to work. I then desactivated the JavaScript, and the order was correct. It seems the JS reorders the contents when loading the page (I assume it's by the contents IDs).
How can I disable this behaviour ? (Only the one made while loading the page, I want my users to be able to reorder by columns).