private void OnTabChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
        {
            grid.ClearGrid();
            Hide3DGrid();
            toolbox.Clear();

            if (StateChanger.SelectedIndex == 0) // Factory-Tab
            {
                csu.isSimulation = false;
                toolbox.Init();
                OnFactorySelected(sender, e);
                BorderArea.Visibility = Visibility.Visible;
            }
            else // Simulation-Tab
            {
                csu.isSimulation = true;
                OnSimulationFactorySelected(sender, e);
                BorderArea.Visibility = Visibility.Hidden;
            }
        }