title: windowBackground does not change with theme
body: <p>I have two themes in my application. I have a blue theme with a blue background:</p>
  
  <pre><code>&lt;style name="Theme.BlueTheme" parent="Theme.Sherlock"&gt;
      &lt;item name="android:panelBackground"&gt;@drawable/menu_hardkey_panel_actionbar&lt;/item&gt;
      &lt;item name="android:buttonStyle"&gt;@style/ButtonAppTheme&lt;/item&gt;
      &lt;item name="android:windowBackground"&gt;@drawable/bground_blue&lt;/item&gt;
      &lt;item name="android:spinnerItemStyle"&gt;@style/SpinnerItem&lt;/item&gt;
      &lt;item name="android:editTextStyle"&gt;@style/Widget.EditText.White&lt;/item&gt;
     &lt;item name="android:spinnerItemStyle"&gt;@style/SpinnerItem&lt;/item&gt;
      &lt;item name="android:textViewStyle"&gt;@style/whitestyle&lt;/item&gt;
  
   &lt;/style&gt;
  </code></pre>
  
  <p>I also have a white theme with a white background:</p>
  
  <pre><code>&lt;style name="Theme.AppTheme" parent="Theme.Sherlock.Light.DarkActionBar"&gt;
      &lt;item name="android:panelBackground"&gt;@drawable/menu_hardkey_panel_actionbar&lt;/item&gt;
      &lt;item name="android:buttonStyle"&gt;@style/ButtonAppTheme&lt;/item&gt;
      &lt;item name="android:windowBackground"&gt;@drawable/bground_white&lt;/item&gt;
      &lt;item name="android:spinnerItemStyle"&gt;@style/SpinnerItem&lt;/item&gt;
      &lt;item name="android:editTextStyle"&gt;@style/Widget.EditText.Black&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>
  
  <p>Everything works fine except the background is always the white one when I set the blue theme in code.</p>
  
  <p>My application theme is set to the white theme in my manifest:</p>
  
  <pre><code>&lt;application
      android:allowBackup="true"
      android:icon="@drawable/launcher_icon"
      android:label="@string/app_name"
      android:theme="@style/Theme.AppTheme" &gt;
  </code></pre>
  
  <p>I then set the blue theme up in my ActivityBase class in onCreate:</p>
  
  <pre><code>@Override
  protected void onCreate(Bundle savedInstanceState) {
  
      super.onCreate(savedInstanceState);
      ActionBar actionBar = getSupportActionBar();
      if (actionBar != null) {
          actionBar.setDisplayHomeAsUpEnabled(true);
      }
      setTheme(R.style.Theme_BlueTheme);
  }
  </code></pre>