Redmine

If I insert code:

<% content_for :header_tags do %>
  <%= stylesheet_link_tag :issue_hot_buttons_sidebar, :plugin => 'issue_hot_buttons_plugin'  %>
<% end %>

in redmine view near hook, it work fine, but in the hook It doesn't work.

For example. init.rb code:

require 'redmine'

class Hooks < Redmine::Hook::ViewListener
    render_on :view_issues_show_details_bottom, :partial => 'assets', :layout => false
end

Redmine::Plugin.register :issue_hot_buttons do
    name 'Issue Hot Buttons Plugin'
    author 'Mike Kolganov, Thumbtack Inc.'
    description 'Plugin for Redmine that add buttons for often used actions to issue page'
    version '0.4.1'
    url 'https://github.com/mikekolganov/redmine-issue-hot-buttons'
end

app/views/issues/_assets.html.erb content is:

<% content_for :header_tags do %>
  <%= javascript_include_tag 'hot_buttons.js', :plugin => 'issue_hot_buttons' %>
  <%= stylesheet_link_tag 'hot_buttons.css', :plugin => 'issue_hot_buttons' %>
<% end %>

Test Test Test!

If I open any issue, I see "Test Test Test!", but links to "hot_buttons.js" and "hot_buttons.css" are absent.

If I modify code in app/views/issues/_assets.html.erb:

  <%= javascript_include_tag 'hot_buttons.js', :plugin => 'issue_hot_buttons' %>
  <%= stylesheet_link_tag 'hot_buttons.css', :plugin => 'issue_hot_buttons' %>

Links appear inside tag "body":

<link href="/plugin_assets/issue_hot_buttons/stylesheets/hot_buttons.css?1339038118" media="screen" rel="stylesheet" type="text/css">
<script src="/plugin_assets/issue_hot_buttons/javascripts/hot_buttons.js?1339107838" type="text/javascript"></script>

I would like include these links in tag "head"