private void stepBackward() {
        index = Math.max(index - 1, 0);
        modelingTimeText.setText(nodes[index] + "ns");
        status("Step backward to node #" + index + " at " + nodes[index] + "ns");
        displayer.updateUITables();
        if(timeDiagramsWindow != null) timeDiagramsWindow.redrawTimeDiagrams(true);
    }