title: Unity and Vuforia virtual button
body: <p>I'm new into Unity + Vuforia, I'm developing an AR app with virtual buttons.
  I have seen lots of videos on youtube and they all use the same method working with Virtual Buttons.
  However, the <code>IVirtualButtonEventHandler</code> seems deprecated, and I haven't seen any alternative sample code for it.</p>
  
  <p><img src="https://i.stack.imgur.com/HRCEz.png" alt="Deprecated warning"></p>
  
  <p>Please help
  Thanks</p>