/**
	 * @not generated
	 */
	@Override
	public void handleNotificationEvent(Notification notification) {
		if (notification.getNotifier() instanceof Grid)
			switch (notification.getFeatureID(Grid.class)) {
			case FormPackage.GRID__CONTENT_FIELD:
				Grid grid = (Grid) notification.getNotifier();

				if (grid.getColumns() != null && !grid.getColumns().isEmpty()) {
					CompositeTransactionalCommand cmd = new CompositeTransactionalCommand(
							getEditingDomain(), null);
					cmd.setTransactionNestingEnabled(false);
					for (int i = 0; i < grid.getColumns().size(); i++) {				
						GridColumn column = (GridColumn) grid.getColumns().get(
								i);	
						
						DestroyElementRequest request = new DestroyElementRequest 
								(column, false);
					
						cmd.add(new DestroyElementCommand(request));
					}
					getDiagramEditDomain().getDiagramCommandStack().execute(new ICommandProxy(cmd));	
				}
				refreshVisuals();
				break;
			}
		super.handleNotificationEvent(notification);
	}

Caused by: java.lang.IllegalStateException: Transaction is already closed
	at org.eclipse.emf.transaction.impl.TransactionImpl.rollback(TransactionImpl.java:533)
	at org.eclipse.gmf.runtime.diagram.core.DiagramEditingDomainFactory$DiagramEditingDomain.postcommit(DiagramEditingDomainFactory.java:223)
	at org.eclipse.emf.transaction.impl.TransactionalEditingDomainImpl.deactivate(TransactionalEditingDomainImpl.java:543)
	at org.eclipse.emf.transaction.impl.TransactionImpl.close(TransactionImpl.java:712)
	at org.eclipse.emf.transaction.impl.TransactionImpl.commit(TransactionImpl.java:474)
	at org.eclipse.emf.workspace.AbstractEMFOperation.execute(AbstractEMFOperation.java:155)
	at org.eclipse.core.commands.operations.TriggeredOperations.execute(TriggeredOperations.java:166)
	at org.eclipse.core.commands.operations.DefaultOperationHistory.execute(DefaultOperationHistory.java:513) ...