preference_dropdown_reselectable.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Mirror of androidx's preference_dropdown_material.xml, with the anchor spinner
  swapped for ReselectableSpinner so re-selecting the current item still fires a
  selection callback. The (invisible) spinner is only the popup anchor; the
  visible row comes from the standard @layout/preference_material include, so the
  appearance is identical to a normal dropdown preference.
-->
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <io.nekohasekai.sagernet.widget.ReselectableSpinner
        android:id="@+id/spinner"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/preference_dropdown_padding_start"
        android:layout_marginLeft="@dimen/preference_dropdown_padding_start"
        android:spinnerMode="dropdown"
        android:visibility="invisible" />

    <include layout="@layout/preference_material" />

</FrameLayout>