title: Modify existing theme
body: <p>I would like to know if it is possible (and how) to customize an existing theme. </p>
  
  <p>What I'm looking for is how can I retrieve a certain attribute (i.e. color) and change it when the <code>Activity</code> starts and reapply the modified theme before <code>setContentView()</code>.</p>
  
  <p>Similar to <code>setTheme()</code>, but instead of using a resource id, use the modified theme.</p>