ReorderableList with Foldout for simplified setting

SimpleReorderableList.cs

/// Copyright (c) 2019 hananoki
/// This code is released under NYSL Version 0.9982
/// See http://www.kmonos.net/nysl/NYSL.TXT

using UnityEngine;

#if UNITY_EDITOR

using UnityEditor;
using UnityEditorInternal;
using System.Reflection;

public class SimpleReorderableList {
  ReorderableList m_lst;

  SerializedObject m_serializedObject;
  SerializedProperty m_serializedProperty;


  public static SimpleReorderableList CreateInstance( SerializedObject serializedObject, string propertyName ) {
    var s = new SimpleReorderableList();
    s.Create( serializedObject, propertyName );
    return s;
  }

  public void Create( SerializedObject serializedObject, string propertyName ) {
    m_serializedObject = serializedObject;
    m_serializedProperty = serializedObject.FindProperty( propertyName );

    m_lst = new ReorderableList( serializedObject, serializedObject.FindProperty( propertyName ) );

    m_lst.drawElementCallback = ( rect, index, isActive, isFocused ) => {
      var rc1 = rect;
      rc1.y += 1;
      rc1.height = EditorGUIUtility.singleLineHeight;

      EditorGUI.PropertyField( rc1, serializedObject.FindProperty( propertyName + ".Array.data[" + index + "]" ) );
    };
    m_lst.drawHeaderCallback = ( rect ) => {
      var rc1 = rect;
      rc1.x += 10;
      string title = string.Empty;
      if( m_serializedProperty.isExpanded ) {
        title = $"{m_serializedProperty.displayName}";
      }
      else {
        title = $"{m_serializedProperty.displayName}  [{m_serializedProperty.arraySize}]";
      }
      m_serializedProperty.isExpanded = EditorGUI.Foldout( rc1, m_serializedProperty.isExpanded, title );
    };

    m_lst.elementHeight = EditorGUIUtility.singleLineHeight + 3;
  }


  public void DoLayoutList() {
    if( m_serializedProperty.isExpanded ) {
      m_lst.DoLayoutList();
    }
    else {
      m_lst.DoListHeader();
    }
  }
}


public static class ReorderableListExtension {
  static FieldInfo _s_Defaults;
  static MethodInfo _DoListHeader;

  public static void DoListHeader( this ReorderableList r ) {
    if( _s_Defaults == null ) {
      _s_Defaults = typeof( ReorderableList ).GetField( "s_Defaults", BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic );
    }
    if( _DoListHeader == null ) {
      _DoListHeader = typeof( ReorderableList ).GetMethod( "DoListHeader", BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic );
    }

    if( _s_Defaults.GetValue( null ) == null ) {
      _s_Defaults.SetValue( null, new ReorderableList.Defaults() );
    }
    var rect = GUILayoutUtility.GetRect( 0f, 18f, GUILayout.ExpandWidth( true ) );
    _DoListHeader.Invoke( r, new object[] { rect } );
  }
}

#endif