title: How change ActionBar colour when swiping between fragments (Material Design)?
body: <p>I have an app i am doing, which has a FragmentPagerAdapter setup with 3 fragments to swipe between on the main page.</p>
  
  <p>I have been trying to get it setup so as you swipe between fragments, the action bar changes color (fades in and out).</p>
  
  <p>However i am not sure how i should do this.
  What method is called when you swipe between fragments? I.E where should i put the code to change the action bar colour?</p>
  
  <p>And also how would i get the fade in and out effect (so it fades out one colour into another one)?</p>
  
  <p>I would really appreciate anyones help.</p>
  
  <p>Thanks in advance</p>
  
  <p>Cheers
  Corey :)</p>