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

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

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:id="@+id/catalogue_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            tools:context=".ui.browse.source.browse.BrowseSourceController">

            <ProgressBar
                android:id="@+id/progress"
                style="?android:attr/progressBarStyleLarge"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_gravity="center"
                android:visibility="gone" />

        </LinearLayout>

        <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
            android:id="@+id/fab_filter"
            style="@style/Theme.Widget.FAB"
            android:text="@string/action_filter"
            android:visibility="gone"
            app:icon="@drawable/ic_filter_list_24dp"
            app:layout_anchor="@id/catalogue_view" />

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

    </FrameLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>