tracks/app/views/contexts/show.m.erb

<h2><%=@context.name%></h2>
<%
# select actions from this context
@not_done = @not_done_todos.select {|t| t.context_id == @context.id }

if not @not_done.empty?
  # only show a context when there are actions in it
-%>
<ul class="c">
<%= render :partial => @not_done, :locals => { :parent_container_type => "context" }-%>
</ul>
<% end -%>