Add a divider between the roots selector and files list.

        android:layout_height="0dp"

        android:layout_weight="1"

        android:orientation="horizontal"

        android:baselineAligned="false">

        android:baselineAligned="false"

        android:divider="?android:attr/dividerVertical"

        android:showDividers="middle">

        <FrameLayout

            android:id="@+id/container_roots"