FairphonePeaceOfMind/res/drawable/secondary_progressbar_progress.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item android:id="@android:id/background">
        <shape>
            <solid android:color="#00000000" />
        </shape>
    </item>
    <item android:id="@android:id/secondaryProgress">
        <clip android:drawable="@drawable/widget_progressbar_progress" />
    </item>
    <item android:id="@android:id/progress">
        <clip android:drawable="@drawable/widget_progressbar_progress" />
    </item>

</layer-list>