title: Setting header colour in the new Material DatePicker
body: <p>So am trying to change the colour of the header of my DatePicker. It doesn't appear to as easy as first though. You can do it in the XML like so:</p>
  
  <pre><code>android:headerBackground="@color/myColor" /&gt;
  </code></pre>
  
  <p>However there doesn't seem to be a way to be able to do this in code. The usual setters don't seem to be apparent (i.e <code>datePicker.setHeaderBackground</code>).</p>
  
  <p>Any ideas?</p>