title: Android doesn't apply background color when a shape is defined
body: <p>I'm trying to create a style for buttons in my app. In order to do that, I created a drawable file with the corner tag. I also created different styles for different button state (normal and disabled). When I apply the style without setting the background attribute, the button have the correct color. But when I set the background attribute with my drawable file, the text color defined in the style.xml works but not the background color. Here is the code : <br><br>
  values/style.xml :</p>
  
  <pre><code>&lt;style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"&gt;
      &lt;item name="android:background"&gt;@color/background&lt;/item&gt;
      &lt;item name="android:textColor"&gt;@color/text_color&lt;/item&gt;
  &lt;/style&gt;
  
  &lt;style name="ButtonStyle"&gt;
      &lt;item name="android:background"&gt;@color/button_color&lt;/item&gt;
  &lt;/style&gt;
  
  &lt;style name="ButtonDisableStyle"&gt;
      &lt;item name="android:background"&gt;@color/button_color_disabled&lt;/item&gt;
      &lt;item name="android:textColor"&gt;@color/buttonText_color_disabled&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>
  
  <p>drawable/button_shape.xml :</p>
  
  <pre><code>&lt;shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" &gt;
  &lt;corners
      android:radius="5dp" /&gt;
  
  &lt;padding
      android:left="0dp"
      android:top="0dp"
      android:right="0dp"
      android:bottom="0dp" /&gt;
  &lt;/shape&gt;
  </code></pre>
  
  <p>main_activity :</p>
  
  <pre><code>&lt;Button
      android:id="@+id/newButton"
      android:text="@string/generate_first"
      style="@style/ButtonStyle"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="center"
      android:layout_weight="30"
      android:background="@drawable/button_shape"
      /&gt;
  </code></pre>
  
  <p>I saw several post about the same problem and I know that it is possible to define the button's background color in the drawable/button_shape.xml but I'd like to keep the style and make it works (I want the shape and the style to be separated). <br>
  Do you have any idea about it ?</p>