title: Does angular-material md-menu component support sub-menus?
body: <p>I see a sub-menu working in the "menu bar" example - <a href="https://material.angularjs.org/latest/demo/menuBar" rel="nofollow">https://material.angularjs.org/latest/demo/menuBar</a></p>
  
  <p>There are no examples of sub-menus for the actual <a href="https://material.angularjs.org/latest/demo/menu" rel="nofollow">menu component</a>.</p>
  
  <p>I looked at the menu bar example and it uses <code>md-menu</code>, so it should be supported in the regular menu, right? I tried it and it breaks the entire menu (top level also stops working).</p>
  
  <p>I'm guessing that it's just not supported? I found <a href="https://github.com/angular/material/issues/78" rel="nofollow">this discussion</a>, but I'm not sure what to make of it.</p>