Displaying tooltip on mouse hover of a text

Question

I want to display a tooltip when the mouse hovers over a link in my custom rich edit control. Consider the following text:

We all sleep

Answer 1

Well, take a look, this works, If you have problems please tell me:

using System.Drawing;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1() { InitializeComponent(); }

        ToolTip tip = new ToolTip();
        void richTextBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (!timer1.Enabled)
            {
                string link = GetWord(richTextBox1.Text, richTextBox1.GetCharIndexFromPosition(e.Location));
                //Checks whether the current word i a URL, change the regex to whatever you want, I found it on www.regexlib.com.
//you could also check if current word is bold, underlined etc. but I didn't dig into it.
                if (System.Text.RegularExpressions.Regex.IsMatch(link, @"^(http|https|ftp)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(:[a-zA-Z0-9]*)?/?([a-zA-Z0-9\-\._\?\,\'/\\\+&%\$#\=~])*$"))
                {
                    tip.ToolTipTitle = link;
                    Point p = richTextBox1.Location;
                    tip.Show(link, this, p.X + e.X,
                        p.Y + e.Y + 32, //You can change it (the 35) to the tooltip's height - controls the tooltips position.
                        1000);
                    timer1.Enabled = true;
                }
            }
        }

        private void timer1_Tick(object sender, EventArgs e) //The timer is to control the tooltip, it shouldn't redraw on each mouse move.
        {
            timer1.Enabled = false;
        }

        public static string GetWord(string input, int position) //Extracts the whole word the mouse is currently focused on.
        {
            char s = input[position];
            int sp1 = 0, sp2 = input.Length;
            for (int i = position; i > 0; i--)
            {
                char ch = input[i];
                if (ch == ' ' || ch == '\n')
                {
                    sp1 = i;
                    break;
                }
            }

            for (int i = position; i < input.Length; i++)
            {
                char ch = input[i];
                if (ch == ' ' || ch == '\n')
                {
                    sp2 = i;
                    break;
                }
            }

            return input.Substring(sp1, sp2 - sp1).Replace("\n", "");
        }
    }
}