求救！急！模仿给控件写个类似于Padding的属性

Question

自己写了封装了个控件，想放出一个类似于Padding的属性来。怎么写着个结构？都有哪些需要必须重写的函数？
下面是我写的，放出去的属性是只读的，而且也没有列表。/////////////////////////////////////////////////////
    public struct KeyList
    {
        public bool Up
        {
            get { return pbUp; }
            set { pbUp = value; }
        }
        public bool Down
        {
            get { return pbDown; }
            set { pbDown = value; }
        }
        public bool Left
        {
            get { return pbLeft; }
            set { pbLeft = value; }
        }
        public bool Right
        {
            get { return pbRight; }
            set { pbRight = value; }
        }        private bool pbUp;
        private bool pbDown;
        private bool pbLeft;
        private bool pbRight;        public override string ToString()
        {
            return pbUp.ToString() 
                + ","
                + pbDown.ToString()
                + ","
                + pbLeft.ToString()
                + ","
                + pbRight.ToString();
        }        public override int GetHashCode()
        {
            return base.GetHashCode();
        }
    }
/////////////////////////////////////////////////////
        private KeyList pbKeyActions;
/////////////////////////////////////////////////////
        [Browsable(true), Category("UserProperties"),
        Description("UseExtraKeyActions")]
        public KeyList UseExtraKeyActions
        {
            get
            {
                return pbKeyActions;
            }
            set
            {
                pbKeyActions = value;
            }
        }
/////////////////////////////////////////////////////