ImageButton example doesn't work. Default state should be at the last.

 * <pre>

 * <?xml version="1.0" encoding="utf-8"?>

 * <selector xmlns:android="http://schemas.android.com/apk/res/android">

 *     <item android:drawable="@drawable/button_normal" /> <!-- default -->

 *     <item android:state_pressed="true"

 *           android:drawable="@drawable/button_pressed" /> <!-- pressed -->

 *     <item android:state_focused="true"

 *           android:drawable="@drawable/button_focused" /> <!-- focused -->

 *     <item android:drawable="@drawable/button_normal" /> <!-- default -->

 * &lt;/selector&gt;</pre>

 *

 * <p>Save the XML file in your project {@code res/drawable/} folder and then