final Object selectedItem = expressionEditor.getSelectedItem();
if (selectedItem instanceof FormulaExpression)
{
final FormulaExpression fe = (FormulaExpression) selectedItem;
final FormulaEditorDialog dialog = GUIUtils.createFormulaEditorDialog(getReportDesignerContext(), carrierPanel);
final String formula = dialog.editFormula(fe.getFormula(), getFields());
if (formula == null)
{
// cancel pressed ... do nothing ...
return;
}