public bool RemoveSizeChangedListener(SizeChangedCallback callback, object userData)
    {
        SizeChangedListener item = new SizeChangedListener();

        item.SetCallback(callback);
        item.SetUserData(userData);
        return(this.m_sizeChangedListeners.Remove(item));
    }
    public bool AddSizeChangedListener(SizeChangedCallback callback, object userData)
    {
        SizeChangedListener item = new SizeChangedListener();

        item.SetCallback(callback);
        item.SetUserData(userData);
        if (this.m_sizeChangedListeners.Contains(item))
        {
            return(false);
        }
        this.m_sizeChangedListeners.Add(item);
        return(true);
    }