title: Custom seek bar not showing the background color
body: <p>I am using the following seekbar</p>
  
  <pre><code>&lt;SeekBar
      android:id="@+id/sbCardSpeed"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:layout_marginRight="5dp"
      android:max="100"
      android:progress="50"
      android:progressDrawable="@drawable/seekbar_progress"/&gt;
  </code></pre>
  
  <p>seekbar_progress.xml:</p>
  
  
  
  <pre><code>&lt;layer-list xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:id="@android:id/background"
          android:drawable="@drawable/background_fill"
      /&gt;
  
      &lt;item
          android:id="@android:id/progress"
          android:drawable="@drawable/seekbar_progress_bg"
      /&gt;
  &lt;/layer-list&gt;
  </code></pre>
  
  <p>background_fill.xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;shape xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;gradient 
          android:startColor="#FFFFFF" //white color
          android:centerColor="#FFFFFF"
          android:endColor="#FFFFFF"
          android:angle="90" /&gt;
  
  &lt;/shape&gt;
  </code></pre>
  
  <p>seekbar_progress_bg.xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;shape xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;gradient 
          android:startColor="#FF8400"  //orange color
          android:centerColor="#FF8400"
          android:endColor="#FF8400"
          android:angle="90" /&gt;
  
  &lt;/shape&gt;
  </code></pre>
  
  <p>The problem that the progress bar is one color which is the orange color. If I move the thumb it is still orange on both sides. The white background is not showing. What is it that I am doing wrong?</p>
  
  <p>Thank you
  <img src="https://i.stack.imgur.com/6DWve.png" alt="enter image description here"></p>