res/drawable/wallpaper_quick_switch_option_selection_marker_background.xml

<?xml version="1.0" encoding="utf-8"?><!--
  ~ Copyright (C) 2023 The Android Open Source Project
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  ~
  -->

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- Inner border -->
    <item>
        <shape android:shape="rectangle">
            <stroke
                android:color="@color/color_surface"
                android:width="8dp" />
            <corners android:radius="12dp" />
        </shape>
    </item>

    <!-- Outer border -->
    <item>
        <shape android:shape="rectangle">
            <stroke
                android:color="@color/text_color_primary"
                android:width="2dp" />
            <corners android:radius="12dp" />
        </shape>
    </item>
</layer-list>