private void txtBxWidth_LostFocus(object sender, RoutedEventArgs e)
        {
            double temp;

            if (Double.TryParse(txtBxWidth.Text, out temp))
            {
                foreach (node n in nodes)
                {
                    n.DisplayShape.Width = temp;
                    gui.NodePropertyChanged(n);
                }
                //Update();
            }
        }