title: state_checked doesn't toggle imageview on and off
body: <p>Android Studio 2.0 preview</p>
  
  <p>Hello,</p>
  
  <p>I have this selector that is connected to an <code>imageview</code>. I want to toggle the <code>imageview</code> on and off. So off will display a green color and on will display a red color.</p>
  
  <p>However, when I click the <code>imageview</code> nothing happens. I have tried different combinations of state_pressed and state_checked. And now its getting too confusing. What am I missing here.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:state_checked="false" 
            android:drawable="@drawable/bottom_left_border"/&gt;
  
      &lt;item android:state_checked="true"
            android:drawable="@drawable/bottom_left_border_pressed"&gt;
      &lt;/item&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p>Many thanks for any suggestions,</p>