title: MenuItem setVisible(false) do not work in Android
body: <p>I put my MenuItem in onPrepareOptionsMenu(Menu menu) and set visible false but there is no change.</p>
  
  <pre><code>public boolean onPrepareOptionsMenu(Menu menu) {
    MenuItem mi = menu.findItem(R.id.example);
    mi.setVisible(false);
    return true;
  }
  
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflater(R.menu.main_menu, menu);
    // ...
  }
  </code></pre>
  
  <p>There are no exceptions or syntax errors.</p>