ReorderableListのフッターの位置を変更するサンプル

TestWindowReorderableListFooterChange.cs

namespace hoge
{
    using UnityEngine;
    using UnityEditor;
    using UnityEditorInternal;
    using System.Collections.Generic;

    public class TestWindowReorderableListFooterChange : EditorWindow
    {
        [SerializeField] private List<int> intList = new List<int>();
        [SerializeField] private ReorderableList reorderableList;

        [MenuItem("EditorWindow/ReorderableListのフッターの位置を変更するサンプル")]
        static void Open()
        {
            GetWindow<TestWindowReorderableListFooterChange>();
        }

        /// <summary>
        /// ウィンドウの描画処理
        /// </summary>
        void OnGUI()
        {
            if (reorderableList == null)
            {
                this.reorderableList = CreateReorderableList(this.intList);
            }

            this.reorderableList.DoLayoutList();
        }

        /// <summary>
        /// ReorderableListの作成
        /// </summary>
        static ReorderableList CreateReorderableList(List<int> intList)
        {
            var list = new ReorderableList(intList, typeof(int));

            // ヘッダー
            Rect headerRect = default(Rect);
            list.drawHeaderCallback = (rect) =>
            {
                headerRect = rect;
                EditorGUI.LabelField(rect, "ヘッダー");
            };

            // フッター
            list.drawFooterCallback = (rect) =>
            {
                rect.y = headerRect.y + 3f;
                ReorderableList.defaultBehaviours.DrawFooter(rect, list);
            };

            // リスト要素
            list.drawElementCallback = (rect, index, isActive, isFocused) =>
            {
                rect.y += 3f;
                rect.height -= 6f;
                intList[index] = EditorGUI.IntField(rect, "Element " + index, intList[index]);
            };
            return list;
        }
    }
}

Thanks!