title: actionbarsherlock getSupportActionBar() return null in android4.0,but in 2.3.3 is ok
body: <p>application use actionbarsherlock,but main activity get getsupportactionbar returns null.
  AndroidManifest.xml:</p>
  
  <pre><code>    &lt;application
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/Light1Theme" &gt;
      &lt;activity
          android:name=".activity.LogonActivity"
          android:configChanges="orientation|keyboardHidden"
          android:windowSoftInputMode="adjustUnspecified|stateHidden" &gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
      ...
  </code></pre>
  
  <p>themes.xml:</p>
  
  <pre><code>    &lt;style name="Light1Theme" parent="Theme.Sherlock.Light"&gt;
  </code></pre>
  
  <p>LogonActivity.ava</p>
  
  <pre><code>    extends SherlockActivity implements OnSharedPreferenceChangeListener {
      ...
      public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      //requestWindowFeature(Window.FEATURE_NO_TITLE);
      //getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,  WindowManager.LayoutParams.FLAG_FULLSCREEN);       
  
      setContentView(R.layout.logon);
  
      try{
      final ActionBar ab = getSupportActionBar();
      //return null
      ab.setBackgroundDrawable(getResources().getDrawable(R.drawable.ab_bg_black));
      getSupportActionBar().setIcon(R.drawable.hospital);
      }catch(Exception e){
          Log.e("", e.getMessage());
      }
  </code></pre>