buttonsPanel.add(editButton, null);
buttonsPanel.add(saveButton, null);
buttonsPanel.add(reloadButton, null);
buttonsPanel.add(exportButton, null);
grid.setController(new GridController() {
/**
* Method invoked when the user has clicked on save button and the grid is in EDIT mode.
* @param rowNumbers row indexes related to the changed rows
* @param oldPersistentObjects old value objects, previous the changes