title: Android menu bar on the bottom
body: <p>I am wanting to implement a menu bar on the bottom of my app like I see in a lot of major apps like facebook, google +, stumble etc. (see image below)</p>
  
  <p>The key aspects of this are that it is overlayed on top of the actual content, and as you scroll down, it disappears, but as you scroll up it comes back.</p>
  
  <p>Since a bunch of apps use this kind of construct I was wondering if there is a simple way to do it and I'm just missing something, or if it actually is quite complicated but these big companies just hire really good developers?</p>
  
  <p>Any pointers on how to go about this would be appreciated. </p>
  
  <p><br/></p>
  
  <p><img src="https://i.stack.imgur.com/LaqEA.jpg" alt="facebook bottom bar"> </p>