public void handleEvent(Event arg0) {
TreeItem[] selection = courses.getSelection();
try {
for (int i = 0; i < selection.length; i++) {
if(!selection[i].getText(0).equals("")) {
system.execute(new RemoveRegistrationItem(idRegistration, selection[i].getText(1)));
selection[i].dispose();
}
}
courses.notifyListeners(SWT.Modify, new Event());
} catch (TransactionDateException e) {