title: progressbar in the middle of a button
body: <p>I want to create a progress bar <strong>in the middle</strong> of a standard button, something like this : 
  <a href="https://i.stack.imgur.com/KQHqm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/KQHqm.png" alt="progressbar"></a></p>
  
  <p>In the xml layout, when i click the progressbar, i do see that it's located where i wish it to be, but on realtime, i can't see it, it feels like its hiding below the button.
  <a href="https://i.stack.imgur.com/LIjZV.png" rel="noreferrer"><img src="https://i.stack.imgur.com/LIjZV.png" alt="android studio xml"></a></p>
  
  <p>I've tried : </p>
  
  <ol>
  <li>Changing the view's positioning (button above/below progressbar)</li>
  <li>indeterminate</li>
  <li>Playing with ProgressBar's style</li>
  </ol>
  
  <p>Nothing seemed to be working. </p>
  
  <p>Here's my xml : </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="wrap_content"
      android:layout_height="match_parent"&gt;
  
      &lt;Button
          android:id="@+id/button_id"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_margin="10dp"
          android:elevation="1dp"
          android:text="test button" /&gt;
  
      &lt;ProgressBar
          android:id="@+id/progress"
          style="?android:attr/progressBarStyleSmall"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignBottom="@+id/button_id"
          android:layout_alignTop="@+id/button_id"
          android:layout_centerHorizontal="true"
          android:indeterminate="true"
          android:indeterminateTint="@android:color/holo_blue_dark"
          android:visibility="visible" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>