title: Using selectors to make partial lines full on Android
body: <p>I've got a requirement have a row of buttons which, when unpressed, have a series of indented lines separating them like so.<img src="https://i.stack.imgur.com/LA9iM.png" alt="enter image description here"></p>
  
  <p>When any of the buttons is clicked, I want the lines surrounding the clicked  button to extend to be full length like so:<img src="https://i.stack.imgur.com/demHe.png" alt="enter image description here"></p>
  
  <p>I've tried implementing this as a selector, but the problem I keep running into is that I can't have each button "own" both of its border lines.  For example, I can set up selectors such that each button has <code>android:right="1px"</code>, and alters its length via a new selector with <code>android:state_pressed="true"</code> but that means that the other buttons would not be able to alter their left border when they're clicked.</p>
  
  <p>I know I could handle this pattern in code, but I feel like it would be ugly and hacky.  Is there any way to implement this in pure XML using a selector?  Also, note that I am using custom components which know whether they are on the left, right, or middle of a list.</p>