tachiyomi/app/src/main/res/layout/material_fastscroll.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="match_parent">

    <View
        android:id="@+id/fast_scroller_bar"
        android:layout_width="7dp"
        android:layout_height="match_parent"
        android:layout_gravity="end"
        android:background="@android:color/transparent"/>

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end">

        <!-- No margin, use padding at the handle -->
        <com.google.android.material.textview.MaterialTextView
            android:elevation="5dp"
            android:id="@+id/fast_scroller_bubble"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="end|center_vertical"
            android:layout_toStartOf="@+id/fast_scroller_handle"
            android:background="@drawable/bubble_drawable"
            android:gravity="center"
            android:paddingStart="12dp"
            android:paddingEnd="12dp"
            android:paddingTop="8dp"
            android:paddingBottom="8dp"
            android:textColor="?actionBarTintColor"
            android:textSize="15sp"
            android:visibility="gone"
            tools:text="A"
            tools:visibility="visible"/>

        <!-- Padding is here to have better grab -->
        <ImageView
            android:id="@+id/fast_scroller_handle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentEnd="true"
            android:contentDescription="@null"
            android:paddingStart="6dp"
            android:paddingEnd="4dp"
            android:src="@drawable/thumb_drawable"/>

    </RelativeLayout>

</merge>