C#TextBox 失去与获取焦点事件

textBox5.LostFocus += new EventHandler(txt_LostFocus); //失去焦点后发生事件
            textBox5.GotFocus += new EventHandler(txt_GotFocus);  //获取焦点前发生事件
            textBox5.MouseClick += new MouseEventHandler(textBox5_MouseClick); // 鼠标点击事件