private void Undo()
        {
            if (currentId > 0)
            {
                //BtnRedo.IsEnabled = true;
                ImageBrush myBrush = new ImageBrush();
                string packUri = "pack://application:,,,/Wpf;component/Images/BtnRedo.png";
                myBrush.ImageSource = new ImageSourceConverter().ConvertFromString(packUri) as ImageSource;
                BtnRedo.Background = myBrush;

                currentId--;

                myCanvas.Children.Clear();
                Model model = new Model();
                model = (Model)model.DeepClone(dataSaver.LoadData("c:/log/" + currentId.ToString()));
                dataObject = model;
                ShowInCanvas(dataObject);
                if (currentId == 0)
                {
                    myBrush = new ImageBrush();
                    packUri = "pack://application:,,,/Wpf;component/Images/BtnUndoNotActive.png";
                    myBrush.ImageSource = new ImageSourceConverter().ConvertFromString(packUri) as ImageSource;
                    BtnUndo.Background = myBrush;
                }
            }
            else
            {
                ImageBrush myBrush = new ImageBrush();
                string packUri = "pack://application:,,,/Wpf;component/Images/BtnUndoNotActive.png";
                myBrush.ImageSource = new ImageSourceConverter().ConvertFromString(packUri) as ImageSource;
                BtnUndo.Background = myBrush;
            }
        }