[RichTextBoxEntension] – Anexar texto multilinha / multicolor

public static class RichTextBoxExtensions
    {
        public static void AppendText(this RichTextBox oBox, string sText, Color oColor)
        {
            oBox.SelectionStart = oBox.TextLength;
            oBox.SelectionLength = 0;
            oBox.SelectionColor = oColor;
            oBox.AppendText(sText + "rn");
            oBox.SelectionColor = oBox.ForeColor;
            oBox.ScrollToCaret();
        }
    }