Sometimes you need to slow down Capybara until certain things have loaded(like javascript assets loaded with RequireJS), here's a solution I came up with:

gistfile1.rb

#/spec/support/asynchronous_helper.rb
module AsynchronousHelper
  
  def wait_until_remote_events_are_bound
    page.wait_until do
      page.evaluate_script("typeof($assetsloaded) === 'object'")
    end
  end
  
  def wait_until_overlay_has_popped_up
    page.wait_until do
      page.evaluate_script("$('div.overlay').is(':visible')")
    end    
  end

  def wait_until_overlay_disappears
    page.wait_until do
      !page.evaluate_script("$('div.overlay').is(':visible')")
    end
  end
end

wait_until has been removed now though, have you a workaround?