自定义控件-只有横线的文本输入框(TxtLine)

需求：在实际开发中，由于TextBox控件的背景色样式不美观，且TextBox不能直接设置背景颜色，因此需要使用自定义控件以实现如下效果

实现代码

public partial class TxtLine : TextBox
    {
        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern IntPtr LoadLibrary(string lpFileName);

        public TxtLine()
        {
            InitializeComponent();
            this.Multiline = true;
            this.Width = 100;
            this.Height = 16;
            this.BorderStyle = BorderStyle.None;
            this.TextAlign = HorizontalAlignment.Center;

        }

        public string DataField
        { get; set; }
        public string Description
        { get; set; }

        private Color _linecolor = Color.Black;
        public Color LineColor
        {
            get
            {
                return this._linecolor;
            }
            set
            {
                this._linecolor = value;
                this.Invalidate();
            }
        }

        private const int WM_PAINT = 0xF;
        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == WM_PAINT)
            {
                DrawLine();
            }
        }
        private void DrawLine()
        {
            Graphics g = this.CreateGraphics();
            using (Pen p = new Pen(this._linecolor))
            {
                g.DrawLine(p, 0, this.Height - 1, this.Width, this.Height - 1);
            }
        }
        protected override void OnPaint(PaintEventArgs pe)
        {
            base.OnPaint(pe);
        }
        protected override CreateParams CreateParams
        {
            get
            {
                CreateParams prams = base.CreateParams;
                if (LoadLibrary("msftedit.dll") != IntPtr.Zero)
                {
                    prams.ExStyle |= 0x020;
                    prams.ClassName = "RICHEDIT50W";
                }
                return prams;
            }
        }

    }