title: Android - Add custom layout to popup menu item
body: <p>I've been working at this now for a while. I'm trying to create a PopupMenu whose top most item looks different then all the rest of the items - essentially a header item that contains a title. </p>
  
  <p>I've tried setting an android:actionLayout for that item, linking that particular item to an xml file that should generate the desired layout. However, this seems to have absolutely no effect. From there I tried to set the actionView programmatically - creating a custom view and then setting it to the item. Still no effect. </p>
  
  <p>I've done research here on SO and looked a at least 10 tutorials; maybe I just suck at Googling today, but I cannot find a way to do this.</p>
  
  <p>Here was my last attempt:</p>
  
  <pre><code>// * my_menu.xml
  &lt;menu
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"&gt;
      &lt;group 
          android:id="@+id/menu_title_group" &gt;
          &lt;item 
              android:id="@+id/menu_title_item"
              android:title=""
              app:actionLayout="@layout/popup_menu_title_header_layout" /&gt;
      &lt;/group&gt;
  &lt;/menu&gt;
  </code></pre>
  
  <p>And then...</p>
  
  <pre><code>// * popup_menu_title_header_layout.xml
  &lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;TextView
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      android:id="@+id/popup_menu_title_header_text_view"
      android:layout_width="wrap_content"
      android:layout_height="match_parent"
      android:layout_marginStart="8dp"
      android:layout_marginLeft="8dp"
      android:layout_marginEnd="8dp"
      android:layout_marginRight="8dp"
      android:gravity="center"
      android:background="@color/red"
      android:textColor="@color/gray"
      android:textSize="16sp"/&gt;
  </code></pre>
  
  <p>And then...</p>
  
  <pre><code>    // * ShowPopupMenu.Activity
      PopupMenu popup = new PopupMenu(getActivity(), showMenuButton);
      popup.getMenuInflater().inflate(R.menu.my_menu, popup.getMenu());
      popup.getMenu().findItem(R.id.menu_title_item).setTitle(some_dynamic_string);
      popup.getMenu().add(1,0,0,"some_dynamic_option_title_1");
      popup.getMenu().add(1,1,0,"some_dynamic_option_title_2");
  </code></pre>
  
  <p>... the popup menu appears exactly as expected, however the top item is not effected at all by the actionLayout. Note that I tried using app:actionLayout, as suggested by some. Also note, I do not want to use a context menu for this.</p>
  
  <p>Thanks in advance!</p>