##view

<div id="comments_area">
        <h3 id="comments_count"><%= pluralize(@article.comments_count, 'comment') %></h3>
        <% cache do %>
        <div id="comments">
                <%= render :partial => @comments %>
        </div>
        <div id="live-preview" style="display: none;" class="markdown">
        </div>
        <div id="new_comment">
                <div id="comment_form">
                
                        <% remote_form_for :comment, :url => comment_article_path(@article), :html => {:id => "comment-form"} do |f| %>
                          <%= render :partial => 'comment_form', :locals => {:f => f, :bt_name => 'comment'} %>
                        <% end %>
                </div>
                <%= render :partial => 'articles/comment_info' %>
        </div>
        <%= observe_form "comment-form",
                                :frequency => 1,
                                :update => "live-preview",
                                :complete => "Element.show('live-preview')",
                                :url => { :action => "preview" } %>
        <% end %>
</div>

##controller

  def preview
    render :layout => false

    respond_to |format| do
      format.js
    end
  end