定制TextBox控件的控制+字母快捷键功能

using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private TextBox textBox1;
        public Form1()
        {
            InitializeComponent();
            textBox1 = new TextBox();
            textBox1.Dock = DockStyle.Top;
            textBox1.ShortcutsEnabled = false; // 禁用定义的快捷方式。
            textBox1.PreviewKeyDown += new PreviewKeyDownEventHandler(textBox1_PreviewKeyDown);
            this.Controls.Add(textBox1);
        }
        private void textBox1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
        {
            switch (e.KeyData)
            {
                case (Keys.Control | Keys.A):
                    textBox1.SelectAll();
                    break;
                case (Keys.Control | Keys.C):
                    textBox1.Copy();
                    break;
                case (Keys.Control | Keys.X):
                    textBox1.Cut();
                    break;
                case (Keys.Control | Keys.V):