ToolWidget.cs

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

public class ToolWidget : MonoBehaviour {

    public Sprite ToolIcon;

    public Sprite iconLeftControllerLeft;
    public Sprite iconLeftControllerRight;
    public Sprite iconLeftControllerUp;
    public Sprite iconLeftControllerDown;
    public Sprite iconRightControllerLeft;
    public Sprite iconRightControllerRight;
    public Sprite iconRightControllerUp;
    public Sprite iconRightControllerDown;

    public enum ToolDisplayTime {
        WhenPatientIsLoaded,
        WhenNoPatientIsLoaded,
        Always
    };

    public ToolDisplayTime displayTime = ToolDisplayTime.WhenPatientIsLoaded;


    // Use this for initialization
    void Start () {

        // Set material for all texts:
        Material mat = new Material(Shader.Find("Custom/TextShader"));
        mat.renderQueue += 2;   // overlay!
        Component[] texts;
        texts = GetComponentsInChildren( typeof(Text), true );

        if( texts != null )
        {
            foreach (Text t in texts)
                t.material = mat;
        }

        Material material = new Material(Shader.Find("Custom/UIObject"));
        material.renderQueue += 2;  // overlay!
        Component[] images;
        images = GetComponentsInChildren( typeof(Image), true );

        if( images != null )
        {
            foreach (Image i in images)
            {
                if( i.material.name == "Default UI Material")
                    i.material = material;
            }
        }
    }

    public void OnEnable()
    {
        // Move the object to the current anchor (to "helmet" or to controller)
        Invoke ("MoveToUIAnchor",0.0001f);

        InputDeviceManager.instance.setLeftControllerTouchpadIcons (
            iconLeftControllerLeft, iconLeftControllerRight, iconLeftControllerUp, iconLeftControllerDown);

        InputDeviceManager.instance.setRightControllerTouchpadIcons (
            iconRightControllerLeft, iconRightControllerRight, iconRightControllerUp, iconRightControllerDown);
    }

    public void OnDisable()
    {
        // Move the object back to the toolControl:
        Invoke ("MoveBackToToolControl",0.0001f);
    }

    private void MoveToUIAnchor()
    {
        if( ToolUIAnchor.instance != null )
            transform.SetParent (ToolUIAnchor.instance.transform, false);
    }
    private void MoveBackToToolControl()
    {
        transform.SetParent (ToolControl.instance.transform, false);
    }
}