FairEmail/app/src/main/res/drawable/scroll_thumb.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <solid android:color="?attr/colorAccent" />
            <size android:width="9dp" android:height="60dp" />
        </shape>
    </item>
    <item>
        <shape android:shape="rectangle">
            <solid android:color="?attr/colorSeparator" />
            <size android:width="9dp" android:height="60dp" />
        </shape>
    </item>
</selector>