tachiyomi/app/src/main/res/menu/chapter_single.xml

<?xml version="1.0" encoding="utf-8"?>

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item android:id="@+id/action_download"
          android:title="@string/action_download"
          android:icon="@drawable/ic_file_download_white_24dp"
          android:visible="true"
          app:showAsAction="ifRoom"/>

    <item android:id="@+id/action_delete"
          android:title="@string/action_delete"
          android:icon="@drawable/ic_delete_white_24dp"
          android:visible="false"
          app:showAsAction="ifRoom"/>

    <item android:id="@+id/action_mark_as_read"
          android:title="@string/action_mark_as_read"
          android:icon="@drawable/ic_done_all_white_24dp"
          app:showAsAction="ifRoom"/>

    <item android:id="@+id/action_mark_as_unread"
          android:title="@string/action_mark_as_unread"
          android:icon="@drawable/ic_done_all_grey_24dp"
          app:showAsAction="ifRoom"/>

    <item android:id="@+id/action_mark_previous_as_read"
          android:title="@string/action_mark_previous_as_read"/>

</menu>