title: How to show pop up in Xamarin forms. i should not use third party plugins
body: <p>How to show pop up in Xamarin Forms, without using third party plugins such as Rg plugin or x-labs plugin? 
  See attached images.<a href="https://i.stack.imgur.com/c5M3m.png" rel="nofollow noreferrer">enter image description here</a></p>