winfrom-容器控件对象的滚轮事件

滚轮事件发生一定要激活当前的目标控件，比如目标控件要有焦点，事件本身简单，就是MouseWheel

下面举例panel：

PRivate void panelsplit_MouseEnter(object sender, EventArgs e)        {            this.panelsplit.MouseWheel += new MouseEventHandler(panelsplit_MouseWheel);            this.panelsplit.Focus();        }        private void panelsplit_MouseLeave(object sender, EventArgs e)        {            this.panelsplit.MouseWheel -= new MouseEventHandler(panelsplit_MouseWheel);         }        private int sumcount = 0;        private int spacing = 60; //线条间距        private void panelsplit_MouseWheel(object sender, MouseEventArgs e)        {            sumcount += e.Delta; //负的放大，正的缩小            int newsp = sumcount / 120 + spacing;            AddMsg(newsp);            //...            panelsplit.Refresh();            panelsplit.Invalidate();            panelsplit.Update();        }
private void AddMsg(object msg)        {            bool scroll = false;            if (this.listBox1.TopIndex == this.listBox1.Items.Count - (int)(this.listBox1.Height / this.listBox1.ItemHeight))                scroll = true;            this.listBox1.Items.Add(msg);            if (scroll)                this.listBox1.TopIndex = this.listBox1.Items.Count - (int)(this.listBox1.Height / this.listBox1.ItemHeight);            this.listBox1.SelectedIndex = this.listBox1.Items.Count - 1;        }鼠标在控件上时响应滚动，移出的之后删除事件不响应，代码只是demo，具体看自己的设计了