res/values/styles.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="Theme.ADK2" parent="android:style/Theme.Holo">
        <item name="android:actionBarStyle">@style/Theme.ADK2_ActionBar</item>
        <item name="android:windowBackground">@color/window_background</item>
    </style>
    
    <style name="Theme.ADK2_ActionBar" parent="@android:style/Widget.Holo.ActionBar">
        <item name="android:background">@drawable/ab_rainbow_bg</item>
    </style>
</resources>