OpenTracks/src/main/res/drawable/activated_background.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/opentracks_transparent" android:state_activated="true" />
    <item android:drawable="@android:color/transparent" />
</selector>