title: MapFragment gets a dark overlay when used in DialogActivity
body: <p>I'm trying to show a <code>MapFragment</code> of the <code>Android Maps v2 API</code> in an <code>Activity</code> with the <code>@android:style/Theme.DeviceDefault.Light.Dialog.NoActionBar</code> theme. This works fine. However, the map gets a dark overlay:</p>
  
  <p><img src="https://i.stack.imgur.com/t7B7t.png" alt="Dialog"></p>
  
  <p>When I change the theme to <code>@android:style/Theme.DeviceDefault.Light.NoActionBar</code>, the map is shown as it should:</p>
  
  <p><img src="https://i.stack.imgur.com/f4uiA.png" alt="Normal"></p>
  
  <p>This is my xml layout file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical" &gt;
  
      &lt;fragment
          android:id="@+id/mapfragment"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          android:layout_weight="1"
          class="com.google.android.gms.maps.MapFragment" /&gt;
  
      &lt;TextView
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:text="HELLO"
          android:textSize="@dimen/textsize_large" /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>What is happening here?</p>