C#

colNum = (Cursor.Position.X - this.stormParent.HorizontalScroll.Value) / charWidth - charWidth;
lineNum = (Cursor.Position.Y - this.stormParent.VerticalScroll.Value) / (int)this.Font.Size - (int)this.Font.Size;

xPixel=(textColumnNumber-horizontalScrollCount)*textCharacterWidth;

colNum = (Cursor.Position.X / charWidth) + this.stormParent.HorizontalScroll.Value;

colNum = (Cursor.Position.X / charWidth) + this.stormParent.VerticalScroll.Value;
lineNum = (Cursor.Position.Y / (int)this.stormParent.Font.Size) + this.stormParent.HorizontalScroll.Value;

Point p = this.PointToClient(Cursor.Position);
colNum = (p.X / charWidth) + this.stormParent.VerticalScroll.Value;
lineNum = (p.Y / (int)this.stormParent.Font.Size) + this.stormParent.HorizontalScroll.Value;

namespace Storm.TextBox
{
    using System;
    using System.Collections.Generic;
    using System.Drawing;
    using System.Linq;
    using System.Text;

    #region Keyword class
    public class Keyword
    {
        private string _kword = "";
        private Color _kcol = SystemColors.ControlText;
        private Font _kfont = new Font(new Font("Courier New", 10), FontStyle.Regular);

        public Keyword(string keyword, Color color, Font font)
        {
            _kword = keyword;
            _kcol = color;
            _kfont = font;
        }

        public string Keyword
        {
            get { return _kword; }
            set { _kword = value; }
        }

        public Color KeywordColor
        {
            get { return _kcol; }
            set { _kcol = value; }
        }

        public Font KeywordFont
        {
            get { return _kfont; }
            set { _kfont = value; }
        }
    }
    #endregion

    public class HighlightingSetup
    {
        #region Members
        // The parent member.
        private TextEditor stormParent = null;

        // The dictionary containing data about keywords added.
        private Dictionary<string, Keyword> keywordDic;
        #endregion

        #region Methods
        public void Add(string keyword, Color color, FontStyle fontstyle) 
        {
            keywordDic.Add(keyword, new Keyword(keyword, color,
                new Font(stormParent.Font, fontstyle)));
        }

        public Keyword KeywordFromString(string keyword)
        {
            if (keywordDic.ContainsKey(keyword))
                return keywordDic[keyword];

            return null;
        }

        public void Remove(string keyword)
        {
            if (keywordDic.ContainsKey(keyword))
                keywordDic.Remove(keyword);
        }
        #endregion

        /// <summary>
        /// Initializes the HighlightingSetup.
        /// </summary>
        public HighlightingSetup(TextEditor parent)
        {
            stormParent = parent;
            keywordDic = new Dictionary<string, Keyword>();
        }
    }
}

//...

        // Temporary color and font variables 
        // for redrawing lines.
        private Color[] kColors;
        private Font[] kFonts;

        // The chars that splits a line.
        private char[] Splitters = { ' ', '(', ')', '[', ']', '{', '}', '!', '"', 
                                     '#', '$', '%', '&', '/', '=', '?', '+', '-', 
                                     '*', '^', '_', ':', ';', '<', '>', '\\'};

        // Temporary string when redrawing lines.
        private string tempLine = "";
        // An integer member for looping.
        private int maxKeywordCount = 0;

        private void HighlightLine(int lineNum)
        {
            string splitString = doc.GetLineFromIndex(lineNum);
            string[] keywords = splitString.Split(Splitters);
            int keywordCount = 0;

            foreach (string keyword in keywords)
            {
                // Set the colors and fonts by index
                // matching keywordCount, so we now
                // what colors and fonts to use for
                // each word in the line. 
                Keyword kw = setup.KeywordFromString(keyword);
                kColors[keywordCount] = kw.KeywordColor;
                kFonts[keywordCount] = kw.KeywordFont;

                tempLine += keyword + "+";

                keywordCount++;
            }

            maxKeywordCount = keywordCount;
            tempLine = tempLine.Substring(0, tempLine.Length - 1); // Remove the last "+".

            // Redraw when everything has been setup.
            this.Invalidate();
        }

        private void onRepaint(object sender, PaintEventArgs e)
        {
            string splitString = tempLine;
            string[] keywords = splitString.Split('+');
            int keywordCount = 0;

            foreach (string keyword in keywords)
            {
                Keyword kw = setup.KeywordFromString(keyword);
                Color kcolor = kw.KeywordColor;
                Font kfont = kw.KeywordFont;

                // Draw the keyword with the correct color.
                StringFormat strFormat = new StringFormat(StringFormatFlags.NoWrap);
                Rectangle posRect = new Rectangle(0, 0, 0, 0); // Use some fancy formula to figure out where to position the text.
                ControlPaint.DrawStringDisabled(e.Graphics, keyword, kfont, kcolor, 
                                                posRect, strFormat);
                ControlPaint.DrawStringDisabled(e.Graphics, " ", this.Font, kcolor,
                                                posRect, strFormat);

                keywordCount++;
            }
        }

Point p = this.PointToClient(Cursor.Position);
colNum = (p.X / charWidth) + this.stormParent.VerticalScroll.Value;
lineNum = (p.Y / (int)this.stormParent.Font.Size) + this.stormParent.HorizontalScroll.Value;

Vestras wrote:

Gives me wrong X and Y locations

public static string test(Guid ID)
{
  if (a == n )
  {
    string abc = x.group;
    return abc;
  }
  else
  {
    return String.Empty;
  }
}

public static string test(Guid ID)
{
  string abc = String.Empty;
  if (a == n )
  {
    abc = x.group;
  }
  return abc;
}