Transform editor rendering the original Unity's editor.

TransformEditorWrapper.cs

using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(Transform))]
public class TransformEditorWrapper : Editor {
	Editor transformEditor;
	
	void OnEnable() {
		Transform transform = target as Transform;
		System.Type t = typeof(UnityEditor.EditorApplication).Assembly.GetType("UnityEditor.TransformInspector");
		transformEditor = Editor.CreateEditor(transform, t);
	}
	
	public override void OnInspectorGUI() {
		GUI.changed = false;
		transformEditor.OnInspectorGUI();

		Transform transform = target as Transform;
		GUILayout.Label("WRAPPED!");
		// do your stuff here...
	}
	
	void OnDisable() {
		DestroyImmediate(transformEditor);
	}
}