title: Set Background as null
body: <p>If I use the following line in the xml layout:</p>
  
  <pre><code>android:background="@null"
  </code></pre>
  
  <ol>
  <li>Is it safe? </li>
  <li>Is effective from a performance point of view? Or
      it's better to set the layout's or the component's bacground from the
      actual code as null?</li>
  </ol>