CanvasRendererMover.cs

using UnityEngine;
using UnityEditor;
using System.Collections;

[CustomEditor(typeof(CanvasRenderer))]
public class CanvasRendererMover : Editor
{
	static int hint = "WidgetHash".GetHashCode();
	void OnSceneGUI()
	{
		if(UnityEditor.Tools.current != Tool.Rect) return;

		var e = Event.current;
		int id = GUIUtility.GetControlID(hint, FocusType.Keyboard);
		var type = e.GetTypeForControl(id);
		if(type != EventType.keyDown) return;

		if(e.keyCode == KeyCode.UpArrow) 			Move(target, new Vector3(0.0f, 1.0f), e);
		else if(e.keyCode == KeyCode.RightArrow)	Move(target, new Vector3(1.0f, 0.0f), e);
		else if(e.keyCode == KeyCode.DownArrow)		Move(target, new Vector3(0.0f, -1.0f), e);
		else if(e.keyCode == KeyCode.LeftArrow)		Move(target, new Vector3(-1.0f, 0.0f), e);
	}

	void Move(object obj, Vector3 v, Event e)
	{
		var g = obj as CanvasRenderer;
		g.transform.localPosition += v;
		e.Use();
	}
}