title: Transparent background showing up as black on api 14-15
body: <p>I have a progress bar which I set its background to be transparent. It works for newer versions of android but on 14 and 15 it shows up as black. Here is my layout:</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingBottom="@dimen/activity_vertical_margin"
  android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  tools:context=".RaceActivity" &gt;
  &lt;ProgressBar
      android:id="@+id/speedometer_view"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_toRightOf="@id/speedometer_title" 
      android:layout_below="@id/current_distance_title" 
      android:padding="8dp" 
      android:background="@android:color/transparent"
      android:progressDrawable="@drawable/speedometer_progress_bar" 
      style="@android:style/Widget.ProgressBar.Horizontal"/&gt;    
  
  &lt;/RelativeLayout&gt; 
  </code></pre>
  
  <p>The theme of my application is android:Theme.Holo.Light.DarkActionBar.</p>
  
  <p>Any ideas how to make it transparent?  </p>