RichTextBoxExtensions.cs

using System;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace Utilities
{
    /// <summary>
    /// Extensions for System.Windows.Forms.RichTextBox
    /// </summary>
    public static class RichTextBoxExtensions
    {
        /// <summary>
        /// Appends colored text to the textbox
        /// </summary>
        /// <param name="textBox">The rich text box</param>
        /// <param name="text">The text to append</param>
        /// <param name="color">The color of the text</param>
        public static void AppendText(this RichTextBox textBox, string text, Color color)
        {
            textBox.SelectionStart = textBox.TextLength;
            textBox.SelectionLength = 0;
            textBox.SelectionColor = color;
            textBox.AppendText(text);
            textBox.SelectionColor = textBox.ForeColor;
        }
    }
}