protected JToolBar createOperatorPanel()
{
final JToolBar operatorButtonPanel = new JToolBar();
operatorButtonPanel.setFloatable(false);
operatorButtonPanel.setOpaque(false);
operatorButtonPanel.setLayout(new HorizontalLayout(2));
operatorButtonPanel.add(new ToolbarButton
(new InsertOperatorAction("+", Messages.getInstance().getString("FormulaEditorDialog.Operator.Add"))));
operatorButtonPanel.add(new ToolbarButton
(new InsertOperatorAction("-", Messages.getInstance().getString("FormulaEditorDialog.Operator.Subtract"))));
operatorButtonPanel.add(new ToolbarButton