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

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <FrameLayout
            android:id="@+id/downloaded_only"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorSecondary"
            android:visibility="gone">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:padding="4dp"
                android:text="@string/label_downloaded_only"
                android:textColor="?attr/colorOnSecondary" />

        </FrameLayout>

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/library_pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </LinearLayout>

    <eu.kanade.tachiyomi.widget.ActionToolbar
        android:id="@+id/action_toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:layout_dodgeInsetEdges="bottom" />

    <eu.kanade.tachiyomi.widget.EmptyView
        android:id="@+id/empty_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="gone" />

</FrameLayout>