title: How to make custom tab with arrow on selected tab?
body: <p>I want to implement tab like design but with an arrow pointing downward when the tab or the view is selected. 
  This is the sample image of what I want to achieve. </p>
  
  <p><img src="https://i.stack.imgur.com/WDvim.png" alt="tab view with arrow pointing downward when selected"></p>
  
  <p>Please anybody help me.</p>