我是一个Unity工具开发人员，我想把一个GUILayout.Label(" title ")放在一个FoldoutHeaderGroup里面，所以我这样做了：

using UnityEditor;
    using UnityEngine;

    public class tesdtEditor : EditorWindow
    {
        private bool showWindowFoldOut;

        [MenuItem("test")]
        public static void ShowWindow()
        {
            EditorWindow.GetWindow(typeof(tesdtEditor));
        }

        public void OnGUI()
        {
            showWindowFoldOut = EditorGUILayout.BeginFoldoutHeaderGroup(showWindowFoldOut, "foldout Name");

            GUILayout.Label("title");

            EditorGUILayout.EndFoldoutHeaderGroup();
        }
    }

但它不在我的FoldoutHeaderGroup（Screen of the window）中
我看不出哪里错了，谁能指点我一下？