MARKUS

    public class ArrowTextControl : CommentUserInfo, IDisposable, INotifyPropertyChanged, IPath, ITextControl, IMarkupControlData,ICommentRect

        public Rect GetCommentRect()

        {

            Rect rect = new Rect();

            rect.Location = new Point();

            rect.Size = new Size();

            List<Point> points = new List<Point>();

            points.AddRange(this.PointSet);

            var boxTopleft = new Point(Canvas.GetTop(Base_TextBox), Canvas.GetLeft(Base_TextBox));

            points.Add(boxTopleft);

            var boxBottomRight =new Point(boxTopleft.X + Base_TextBox.ActualWidth, boxTopleft.Y + Base_TextBox.ActualHeight);

            points.Add(boxBottomRight);

            rect = CommentMath.CalculateBoundingRect(points);

            return rect;

        }