for (int idm = 0; idm < TotalCountMonth; idm++)
                {
                    Rectangle rectMonth = new Rectangle();
                    rectMonth.SetValue(Canvas.LeftProperty,leftNextRect);
                    rectMonth.SetValue(Canvas.TopProperty,topMonthRectangles);
                    double wigthCurRect = countDayInMonth[idm]*sideRectanglDay;
                    rectMonth.Height = heigthMonthScale;
                    rectMonth.Width = wigthCurRect;
                    rectMonth.Stroke = brushLines;

                    Label lblT = new Label();
                    lblT.SetValue(Canvas.LeftProperty,leftNextRect+2.0);
                    lblT.SetValue(Canvas.TopProperty,topMonthRectangles);
                    lblT.Content = namesMonths[dtTempCalcDayInMpnth.Month-1];

                    double r1 = lblT.ActualWidth; // Здесь ActualWidth возвращает просто 0.0
                    canvasDgGant.Children.Add(lblT);
                    double r2 = lblT.ActualWidth; // Здесь ActualWidth тоже возвращает просто 0.0

                    canvasDgGant.Children.Add(rectMonth);
                    leftNextRect += wigthCurRect;
                    dtTempCalcDayInMpnth = dtTempCalcDayInMpnth.AddMonths(1);
                }