title: Django: Passing argument to parent template
body: <p>I have templates of this style</p>
  
  <pre><code>project
  - main_templates (including nav bar)
  -- app1
  --- app1_base_template
  --- app1_templates
  -- app2
  --- app2_base_template
  --- app2_templates
  </code></pre>
  
  <p>So when rendering, app2_templates extends app2_base_template which extends main_template.</p>
  
  <p>What I need to do, is have the corresponding nav item be bold when app2's template is being rendered (to show the user where he is).</p>
  
  <p>The easiest would if I could pass a variable in the {% block xxx %} part. 
  Is this possible ?</p>
  
  <p>What other generic ways are there ?</p>