Unity 4.6 UI Collider Mask

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

[ExecuteInEditMode]
public class UIColliderMask : MonoBehaviour, ICanvasRaycastFilter
{
    private RectTransform _rectTransform = null;

    public RectTransform rectTransform
    {
        get
        {
#if UNITY_EDITOR
            if(!UnityEditor.EditorApplication.isPlaying)
                return GetComponent<RectTransform>();
#endif
            return _rectTransform ?? (_rectTransform = GetComponent<RectTransform>());
        }
    }

    void Update()
    {
        float s = rectTransform.rect.width * colliderAspect;

        colliderGameObject.transform.localScale = new Vector3 (s, s, s);
    }

    public GameObject colliderGameObject = null;

    public float colliderAspect = 0.0f;

    public bool IsRaycastLocationValid(Vector2 screenPosition, Camera raycastEventCamera)
    {
        return colliderGameObject.collider2D.OverlapPoint (screenPosition);
    }
}