title: Convenient way to show touch highlight when clicking Button in Android
body: <p>In iOS, one code line is enough to have button show touch highlight: yourButton.showsTouchWhenHighlighted = YES;</p>
  
  <p>In Android, selector could be used. However, it's quite tedious. For example, if there're 100 button icons in my app, I have to prepare at least 200 button icons: 100 for normal and 100 for highlighted.</p>
  
  <p>Is there any convenient/simpler way to do this?</p>