title: Android SupportActionBar not animating on show / hide
body: <p>I find a lot of questions about how to disable the animation of an Android ActionBar. I have exactly the opposite problem. I do want the animation but it should work out of the box right?</p>
  
  <p>I think the problem lies with my custom toolbar:</p>
  
  <pre><code>&lt;android.support.design.widget.AppBarLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_height="wrap_content"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      android:id="@+id/toolbar_parent"
      android:layout_width="match_parent"
      android:theme="@style/AppTheme.AppBarOverlay"&gt;
  
      &lt;android.support.v7.widget.Toolbar android:id="@+id/toolbar"
          android:layout_width="match_parent" android:layout_height="@dimen/menu_height"
          android:minHeight="@dimen/menu_height"
          android:background="@color/backgroundColor" app:popupTheme="@style/AppTheme.PopupOverlay"
          android:theme="@style/ToolbarColoredBackArrow"/&gt;
  
  &lt;/android.support.design.widget.AppBarLayout&gt;
  </code></pre>
  
  <p>Which I set in mij activity like so:</p>
  
  <pre><code> Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
   setSupportActionBar(toolbar);
  </code></pre>
  
  <p>The toolbar works fine, but no animation when I call either of these methods:</p>
  
  <pre><code>protected void hideActionBar(){
      ActionBar ab = getSupportActionBar();
      if (ab.isShowing()) {
          ab.hide();
      }
  
  }
  
  protected void showActionBar(){
      ActionBar ab = getSupportActionBar();
      if (!ab.isShowing()) {
          ab.show();
      }
  }
  </code></pre>
  
  <p>What is the reason of this?</p>