public void CloseButton()
    {
        GameManager.instance.RemoveItem(thisItem);

        thisItem = GetThisItem();
        if (thisItem != null)
        {
            tooltip.ShowTooltip();
            tooltip.UpdateTooltip(GetDetailText(thisItem));
            RectTransformUtility.ScreenPointToLocalPointInRectangle(GameObject.Find("Canvas").transform as RectTransform, Input.mousePosition, null, out position);
            tooltip.SetPosition(position);
        }
        else
        {
            tooltip.HideTooltip();
            tooltip.UpdateTooltip("");
        }
    }