using System.Runtime.InteropServices;

{
       [DllImport("user32")]
        public static extern bool GetCaretPos(ref   System.Drawing.Point lpPoint);

        private void  GetCurRowNo()
        {
            try
            {
                Point P = new Point(0);
                GetCaretPos(ref   P);
                int Pos = txtCmdInput.GetCharIndexFromPosition(P);
                m_iCurRowNo = txtCmdInput.GetLineFromCharIndex(Pos);

            }
            catch
            {
                m_iCurRowNo = -1;
            }
        }
}