title: cornerRadius not working with backgroungTint
body: <p>I am a beginner in android dev.
  I am making a calculator in which i want to add round button using corner Radius.
  the problem is that it is working fine when i donot set background tint as shown below</p>
  <pre><code>&lt;Button
      android:id=&quot;@+id/button_7&quot;
      android:layout_width=&quot;50dp&quot;
      android:layout_height=&quot;50dp&quot;
      android:text=&quot;7&quot;
      android:textColor=&quot;#000000&quot;
      app:cornerRadius=&quot;20dp&quot; /&gt; 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/wY6r7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wY6r7.jpg" alt="image" /></a></p>
  <p>but when i set background tint it does not work</p>
  <pre><code>&lt;Button
      android:id=&quot;@+id/button_7&quot;
      android:layout_width=&quot;50dp&quot;
      android:layout_height=&quot;50dp&quot;
      android:text=&quot;7&quot;
      android:textColor=&quot;#000000&quot;
      app:cornerRadius=&quot;20dp&quot;
      android:background=&quot;#E3E3E3&quot;
      app:backgroundTint=&quot;#E3E3E3&quot;/&gt;
  </code></pre>
  <p><a href="https://i.stack.imgur.com/Tnaxc.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Tnaxc.jpg" alt="image" /></a></p>
  <p>What should i do? thanks!</p>