NGUIRenderQueue

NGUIParticleRenderQueue.cs

/*
 * This code snippet can adjust the gameobject's renderqueue in NGUI.
 */

using UnityEngine;

[ExecuteInEditMode]
class NGUIParticleRenderQueue : MonoBehaviour
{
    public UIPanel panel;
    public int rendererQOffset = 3000;
    public bool runOnlyOnce = false;

    void Update ()
    {
        Renderer r = renderer;

        if ( panel == null )
        {
            panel = GetComponent<UIPanel>();
        }

        if ( panel != null  && r != null )
        {
            int targetRenderQueue = panel.startingRenderQueue + rendererQOffset;
            if ( targetRenderQueue > 0 )
            {
                r.sharedMaterial.renderQueue = targetRenderQueue;
            }
        }

        if ( runOnlyOnce && Application.isPlaying )
        {
            this.enabled = false;
        }
    }
}

also you can only adjust the render queue

// Just add this line to your code.
r.shaderedMaterial.renderQueue = targetRenderQueue;