UIのみを表示するシーンビュー

UISceneView.cs

using UnityEngine;
using System.Collections;
using UnityEditor;

public class UISceneView : SceneView{
	[MenuItem("Window/UISceneView")]
	static void Init()
	{
		var window = ScriptableObject.CreateInstance<UISceneView> ();

		window.in2DMode = true;
		window.m_SceneLighting = false;
		window.Show ();
	}

	int glovalLayer;

	void OnFocus() {
		glovalLayer =  Tools.visibleLayers;
	}

	void  OnLostFocus() {
		Tools.visibleLayers = glovalLayer;
	}

	void OnGUI()
	{
		var layers =  Tools.visibleLayers;
		Tools.visibleLayers = 32;
		var type = typeof(SceneView);
		var methodOnGUI = type.GetMethod ("OnGUI",
		                                  System.Reflection.BindingFlags.NonPublic | 
		                                  System.Reflection.BindingFlags.Instance);
		methodOnGUI.Invoke (this, null);
		Tools.visibleLayers = layers;
	}
}

how to use

1. create a "Editor" folder in /Assets/ folder.
2. put UISceneView.cs in Editor folder
   
3. select window/ui scene view
   
4. Hide UI layer
   
5. disable skybox in ui scene view