private JMenu setupEditMenu() {
        JMenu edit = new JMenu(Utils.lang("edit"));
        JMenuItem undo = new JMenuItem(Utils.lang("undo"));
        undo.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Z, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        undo.addActionListener(new Undo());
        JMenuItem redo = new JMenuItem(Utils.lang("redo"));
        redo.addActionListener(new Redo());
        edit.add(undo);
        edit.add(redo);
		return edit;
	}