AndroidLauncher3/1300_r15/Code/res/drawable/drop_target_background.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2021 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

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     distributed under the License is distributed on an "AS IS" BASIS,
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<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true"
        android:drawable="@drawable/drop_target_frame_hover" />
    <item android:state_selected="false"
        android:drawable="@drawable/drop_target_frame" />
</selector>