title: CheckboxPreference state is not changed when calling onContentChanged
body: <p>I have a <code>Restore default settings</code>option in my <a href="http://developer.android.com/reference/android/preference/PreferenceActivity.html" rel="nofollow">PreferenceActivity</a>. After the settings are changed I call <a href="http://developer.android.com/reference/android/preference/PreferenceActivity.html#onContentChanged%28%29" rel="nofollow">onContentChanged()</a>. But for some reason the visual state of my <a href="http://developer.android.com/reference/android/preference/CheckBoxPreference.html" rel="nofollow">CheckboxPreference</a> is not updated.</p>
  
  <p>The only workaround if found is to update the state manually:</p>
  
  <pre><code>SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
  boolean autoStartValue = prefs.getBoolean("auto_start", true);
  
  CheckBoxPreference autoStartPref = (CheckBoxPreference)findPreference("auto_start");
  autoStartPref.setChecked(autoStartValue);
  
  // Notify that the preferences changed
  EditPreferencesActivity.this.onContentChanged();
  </code></pre>
  
  <p>What is the correct way of doing this?</p>