title: Android fill_parent issue
body: <p>HI there. This is my layout </p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"&gt;
      &lt;ListView android:id="@+id/lv"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:background="@android:color/white" /&gt;
      &lt;Button android:layout_width="wrap_content" 
          android:layout_height="wrap_content"
          android:layout_below="@id/lv" /&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>When I run this the list view occupies full screen. What I want is list view to be full screen except button area without mentioning dp. Thanks</p>