Problem with TextVObject - inherit class (from RectangleVObject)

textVObject.SupportedActions[Aurigma.GraphicsMill.WinControls.VObjectAction.ChangeTextArea].Enabled = true;

    public class FbTextBox : RectangleVObject
    {
        RectangleVObject _shadowRect;
        TextVObject _textRect;


        public FbTextBox(System.Drawing.RectangleF rectangle)
            : base(rectangle)
        {
            _shadowRect = new RectangleVObject(0, 0, 1, 1);
            _shadowRect.Brush = System.Drawing.Brushes.White;
            _shadowRect.Pen = new System.Drawing.Pen(System.Drawing.Color.Gray, 10f);
            _shadowRect.Pen.Alignment = System.Drawing.Drawing2D.PenAlignment.Inset;

            _textRect = new TextVObject();
            _textRect.Pen = new System.Drawing.Pen(System.Drawing.Color.Black, 10f);
            _textRect.Brush = new System.Drawing.SolidBrush(System.Drawing.Color.Gray);
            System.Drawing.Font font=new System.Drawing.Font(new FontFamily("Arial"),32);
            _textRect.Font = font;
            _textRect.Text = "Test";
            
// this line have no effect
_textRect.SupportedActions[Aurigma.GraphicsMill.WinControls.VObjectAction.ChangeTextArea].Enabled = true;
        }

        public override void Draw(System.Drawing.Rectangle renderingRect, System.Drawing.Graphics g, ICoordinateMapper coordinateMapper)
        {
            // das unterste Rechteck zeichnen
            base.Draw(renderingRect, g, coordinateMapper);
            
            System.Drawing.RectangleF _thisObjBounds = this.GetVObjectBounds();

            // Shadow
            System.Drawing.RectangleF _shadowRectBounds = _shadowRect.GetVObjectBounds();
            if (!_shadowRectBounds.Equals(_thisObjBounds))
            {
                System.Drawing.Brush tmpBrush = _shadowRect.Brush;
                System.Drawing.Pen tmpPen = _shadowRect.Pen;

           //     _shadowObjBounds.X += 10;
           //     _shadowObjBounds.Y += 10;
           //     _shadowObjBounds.Width -= 20;
                _shadowRect = new RectangleVObject(_thisObjBounds);
                _shadowRect.Transform = this.Transform;
                _shadowRect.Brush = tmpBrush;
                _shadowRect.Pen = tmpPen;
            }
            _shadowRect.Transform = this.Transform;
            _shadowRect.Draw(renderingRect, g, coordinateMapper);


            // Text
            System.Drawing.RectangleF _textRectBounds = _textRect.TextArea;   
            if (!_textRectBounds.Equals(_thisObjBounds))
            {
                System.Drawing.Brush tmpBrush = _textRect.Brush;
                System.Drawing.Pen tmpPen = _textRect.Pen;
                System.Drawing.Font tmpfont = _textRect.Font;
                string text = _textRect.Text;

                _textRect = new TextVObject(text, tmpfont.Name, 32.0f, _thisObjBounds);
                _textRect.Transform = this.Transform;
                _textRect.Brush = tmpBrush;
                _textRect.Pen = tmpPen;
            }

            // draw text
            _textRect.Transform = this.Transform;
            _textRect.Draw(renderingRect, g, coordinateMapper);
        }



        public System.Drawing.Brush ShadowBrush
        {
            get { return _shadowRect.Brush; }
            set { _shadowRect.Brush = value; }
        }

        public System.Drawing.Pen ShadowPen
        {
            get { return _shadowRect.Pen; }
            set { _shadowRect.Pen = value; }
        }


    }

System.Drawing.RectangleF objBounds = GetTransformedVObjectBounds();

System.Drawing.RectangleF objBounds = GetVObjectBounds();

      // Text
      System.Drawing.RectangleF objBounds = GetTransformedVObjectBounds();
      if (!objBounds.Equals(_textRect.TextArea))
      {
            _textRect.Transform = new System.Drawing.Drawing2D.Matrix();
            _textRect.TextArea = objBounds;
      }                        
      
      // draw text
      _textRect.Draw(renderingRect, g, coordinateMapper);