I\'m using Ruby on Rails (Edge, the development version), and Ruby rvm 1.9.2.
application.js is as follows.
//= require jquery
//= requi
I've fallen down to doing it the old way:
I put the jQuery folder, containing the theme (unchanged with both CSS and images folder) in the assets/stylesheets folder, and putting in: <%= stylesheet_link_tag "jquery/ui-lightness/jquery-ui-1.8.13.custom" %> in app/views/layouts/application.html.erb file. This solution is the one with less hazel when I will update jQuery later.
(Thanks for all suggestions on the solution. It is time to conclude.)