title: setContentView() not working
body: <p>Here's my code:</p>
  
  <pre>
  <code>    
      public class MyActivity extends Activity implements View.OnClickListener {          
          private Button mHorizontalButton;
          private Button mVerticalButton;
  
          public void onCreate(Bundle savedInstanceState) {
              super.onCreate(savedInstanceState);
              setContentView(R.layout.main);
              mHorizontalButton = (Button) findViewById(R.id.horizontal_button);
              mVerticalButton = (Button) findViewById(R.id.vertical_button);
              mHorizontalButton.setOnClickListener(this);
              mVerticalButton.setOnClickListener(this);
          }
  
          public void onClick(View v) {
              switch (v.getId()) {
                  case R.id.horizontal_button:
                      setContentView(R.layout.horizontal);
                      break;
                  case R.id.vertical_button:
                      setContentView(R.layout.main);
                      break;      
              }
          }
      }
  </code>
  </pre>
  
  <p><strong>main.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
      &lt;TextView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="This layout is vertical." /&gt;
      &lt;Button
          android:text="Click for a horizontal layout"
          android:id="@+id/horizontal_button"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content" /&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p><strong>horizontal.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="horizontal"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
      &lt;TextView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="This layout is horizontal." /&gt;
      &lt;Button
          android:text="Click for a vertical layout"
          android:id="@+id/vertical_button"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content" /&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>It is supposed, that by clicking on button I'll get the horizontal view, and then after clicking once again - vertical. </p>
  
  <p>But after clicking nothing happens. What might be the issue?</p>