TestHierarchyPopupMenuEditor.cs

using UnityEditor;
using UnityEngine;

public class TestHierarchyPopupMenuEditor : ScriptableObject {

    [MenuItem("GameObject/Create New Child", true)]
    private static bool ValidateCreateChild() {
        GameObject[] gameObjects = Selection.gameObjects;
        return gameObjects.Length > 0;
    }

    [MenuItem("GameObject/Create New Child", false, 11)]
    private static void CreateChild() {
        GameObject[] gameObjects = Selection.gameObjects;
        for (int i = 0; i < gameObjects.Length; i++) {
            var child = new GameObject("New Child");
            child.transform.parent = gameObjects[i].transform;
        }
    }
}
 

修改為按下並釋放滑鼠中鍵彈出指定選單
TestHierarchyPopupMenuEditor.cs

using UnityEditor;
using UnityEngine;

public class TestHierarchyPopupMenuEditor : ScriptableObject {

    [InitializeOnLoadMethod]
    private static void StartInitializeOnLoadMethod() {
        EditorApplication.hierarchyWindowItemOnGUI += OnHierarchyGUI;
    }

    private static void OnHierarchyGUI(int instanceID, Rect selectionRect) {
        if (Event.current!=null) {
            Debug.Log($"button:{Event.current.button}, type:{Event.current.type}");
        }
        
        if (Event.current != null && Event.current.button == 2 && Event.current.type == EventType.MouseUp) { // 按下並釋放滑鼠中鍵時
            //if (Selection.activeTransform) { // 選中啟用一個 Transform 時才彈出
                Vector2 mousePosition = Event.current.mousePosition;
                EditorUtility.DisplayPopupMenu(new Rect(mousePosition.x, mousePosition.y, 0, 0), "GameObject/", null); // 彈出 GameObject 選單
            //}
        }
    }
}