title: When button is clicked, how to change Button color in Xamarin.Android app
body: <p>I have no idea why the background color doesn't work. </p>
  
  <p>I want to change color when the button is clicked.</p>
  
  <p>This is the screenshot of the problem:
  <a href="https://gyazo.com/e2b8a9eb269562299bea441c18af4ce0" rel="nofollow noreferrer">https://gyazo.com/e2b8a9eb269562299bea441c18af4ce0</a></p>