title: Selectable circle on a selectableItemBackgroundBorderless widget is truncated
body: <p>I am trying the new <code>?selectableItemBackgroundBorderless</code> background on Android Lollipop to create a circle selector. So far the result looks good, as the picture below. The circle even extends over the "2" and "4" bounds. However the circle is truncated at several sides (top and left at the picture). </p>
  
  <p>Why is it so, and how to make the circle complete?</p>
  
  <p><img src="https://i.stack.imgur.com/N5Jgj.png" alt="truncated circle"></p>