title: GridLayout from support library does not show 2 rows on Android 2, onChildVisibilityChanged Error
body: <p>Has anybody gotten the support library to render a grid layout correctly in Android 2?  Instead of 2 rows and columns I get a single row on the screen and see this error in the logcat output:
  Android GridLayout Could not find method android.support.v7.widget.ViewGroup.onChildVisibilityChanged</p>
  
  <p>The same exact layout is working on Android4 -> ICS when I change the layout tag from
  android.support.v7.widget.GridLayout to GridLayout</p>
  
  <p>Could this be some issue with the setup? I have the gridlayout_v7 library project in the Android tab of my Eclipse project properties and the v.13 jar is on the build path.  </p>
  
  <p>The XML layout that is failing is pasted below.  I added the layout rows and columns explicitly in the image button tags in an effort to work around the problem.  If anybody has a working example that runs on Android 2 with the support library, please share.</p>
  
  <pre><code>&lt;android.support.v7.widget.GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:columnCount="2"  android:rowCount="2"
  android:gravity="center_vertical" 
  android:layout="@drawable/bg_test_main" &gt;
  
  &lt;ImageButton android:id="@+id/btnSentence"
  android:layout_row="0"
  android:layout_column="0"
  android:src="@drawable/testa_btn"
  android:contentDescription="@string/spin_fill_in"
  android:background="@android:color/transparent"
  /&gt;
  &lt;ImageButton android:id="@+id/btnAudio"
  android:layout_row="0"
  android:layout_column="1"
      android:src="@drawable/testb_btn"
  android:contentDescription="@string/audio_quiz"
  android:background="@android:color/transparent"
  /&gt;
  &lt;ImageButton android:id="@+id/btnPickWord"
  android:layout_row="1"
  android:layout_column="0"
  android:src="@drawable/testc_btn"
  android:background="@android:color/transparent"
  android:contentDescription="@string/def_pick_word" /&gt;
  
  &lt;ImageButton android:id="@+id/btnPickDef"
  android:layout_row="1"
  android:layout_column="1"
  android:src="@drawable/testd_btn"
  android:background="@android:color/transparent"
  android:contentDescription="@string/pick_def" /&gt;
  
  &lt;/android.support.v7.widget.GridLayout&gt;
  </code></pre>