About redraw label control

I want to achieve label control text display in front of four characters are white, the latter word is all red.
The following is my code:
<pre lang="c#">
    //I have used: as a separator
    public Rectangle DeflateRect(Rectangle rect, Padding padding)
        {
            rect.X += padding.Left;
            rect.Y += padding.Top;
            rect.Width -= padding.Horizontal;
            rect.Height -= padding.Vertical;
            return rect;
        }


        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);


            Rectangle r = DeflateRect(base.ClientRectangle, base.Padding);

            if (this.Text.Length > 0)
            {
                string[] str = this.Text.Split(new char[] { ':' });
                if (str.Length > 0)
                {
                    TextRenderer.DrawText(e.Graphics,
                       this.Text.Substring(0, str[0].Length + 1), this.Font, r, Color.White, base.BackColor, TextFormatFlags.Left);


                    TextRenderer.DrawText(e.Graphics,
                     this.Text.Substring(str[0].Length + 1, str[1].Length), this.Font, r, Color.Red, base.BackColor, TextFormatFlags.Right);
                }
            }
        }



</pre>

<pre lang="vb">However, I encounter the following problems:
           When &quot;\ naaaaaaaaaaaaaaaaaaaaa \ nbbbbbbbbbbbbbbbbbbb \ nccccccccc&quot; multiple newline character will be displayed when the control word generator and the original offset, it looks like two kinds of color displayed on the control word</pre>