title: Material-UI Dropdown Menu Navigation
body: <p>I am using Material-ui v1 beta and I want to have a series of dropdown Menus across the top for my navigation. This is primarily a web App - - I see the AppBar component with a menu item but not a dropdown and I see the Simple Menu that is a dropdown that would work but it says to not use it for primary navigation. </p>
  
  <p>I am wondering why not?</p>
  
  <p>What is the best practice for navigation?</p>
  
  <p>Any suggestions for a top of the screen dropdown navigation system - preferably tied to react-router ?</p>