<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
        android:drawable="@drawable/button_pressed" />
    <item android:state_focused="true" android:state_enabled="true"
        android:state_window_focused="true"
        android:drawable="@drawable/button_focused" />
    <item
         android:drawable="@drawable/button_background" />
		 <!-- this is where we're setting the default, your shape -->
</selector>