title: Checks not showing in Options Menu
body: <p>Sometimes when doing some so very simple, you miss something big.  I must be missing something huge because I am getting nowhere fast (and an hour of sifting through the web has revealed nothing).</p>
  
  <p>I want to have a menu with items with checkmarks in group--just like a simple RadioGroup layout.  I get the menu, but no checkmarks of any kind.</p>
  
  <p>Here's the res/menu/options_menu.xml:</p>
  
  <pre><code> &lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;menu xmlns:android="http://schemas.android.com/apk/res/android" &gt;
  
      &lt;group android:checkableBehavior="single"&gt;
          &lt;item
              android:id="@+id/item1"
              android:title="item1"
          /&gt;
          &lt;item
              android:id="@+id/item2"
              android:title="item2"
          /&gt;
          &lt;item
              android:id="@+id/item3"
              android:title="item3"
              android:checked="true"
          /&gt;
      &lt;/group&gt;
  
  &lt;/menu&gt;
  </code></pre>
  
  <p>And of course, here's the relevant methods in my Activity:</p>
  
  <pre><code>    @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.options_menu, menu);
      return true;
  }
  </code></pre>
  
  <p>This is about as simple as I can make it--any ideas on what I'm missing?</p>