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