<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
 <item android:state_checked="true"
       android:drawable="@drawable/tb_onstate" /> <!-- pressed -->
 <item android:state_checked="false"
       android:drawable="@drawable/tb_offstate" /> <!-- unchecked -->
</selector>