title: How do I add selectableItemBackground to an ImageButton programmatically?
body: <p>android.R.attr.selectableItemBackground exists, but how do I add it programatically to an ImageButton? </p>
  
  <p>Also, how would I go about finding the answer in the documentation? It's mentioned <a href="https://developer.android.com/reference/android/R.attr.html" rel="noreferrer">here</a>, but I don't see any explanation of how it's actually used. Actually, I rarely seem to find the documentation useful, but I'm hoping that's my fault and not that of the documentation.</p>