title: How to add drop-down controls to navigation drawer
body: <p>As per the title.</p>
  
  <p>I am using the Support Library DrawerLayout to create a sliding drawer that has a listview in it.</p>
  
  <p>I'd like to add some drop-down (spinner) controls so the list can be sorted alphabetically etc.</p>
  
  <p>How can I achieve this?</p>