c# 去掉Form窗口关闭按钮，保留窗体栏

//去掉Form窗口关闭按钮，保留窗体栏，可以拖动：

//重写窗体的CreateParams方法：

        private const int CP_NOCLOSE_BUTTON = 0x200;
        protected override CreateParams CreateParams
        {
            get
            {
                CreateParams myCp = base.CreateParams;
                myCp.ClassStyle = myCp.ClassStyle | CP_NOCLOSE_BUTTON;
                return myCp;
            }