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

<%
new_context_todo_params = {:format => :m}
new_context_todo_params[:from_context] = context.id

# 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
  -%>
<h2><%= link_to context.name, context_path(context, :format => 'm') %><span class="ctx-add"><%= link_to t('+'), new_todo_path(new_context_todo_params) %></span></h2>
<ul class="c">
<%= render :partial => "todos/todo",
           :collection => @not_done,
           :locals => { :parent_container_type => "context" }-%>
</ul>
<% end -%>