Image.fillCenter

Description

Whether or not to render the center of a Tiled or Sliced image.

This will only have any effect if the Image.sprite has borders.

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

public class FillCenterScript : MonoBehaviour
{
    public Image xmasCalenderDoor;

    // removes the center of the image to reveal the image behind it
    void OpenCalendarDoor()
    {
        xmasCalenderDoor.fillCenter = false;
    }
}