Bug 148755 Add tthe status to the ActivityStackEvent.
If the the event rollback, the ActivityStackEvent status should be ROLL_BACK.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/activity/ActivityStack.java
* <p>
	 * Part of: Notification system.
	 * 
	 * @param obj
	 *            the activity stack listener to remove
	 */
	public void removeListener( ActivityStackListener obj )
	{
		if ( listeners == null )
			return;
		int posn = listeners.indexOf( obj );
		if ( posn != -1 )
			listeners.remove( posn );
	}
	/**
	 * Sends the notifications. This method check the current record state, and
	 * fire event to corresponding method of listener.
	 * 
	 * @param event
	 *            activity stack event.
	 */
	protected void sendNotifcations( ActivityStackEvent event )
	{
		
		if ( listeners != null )
		{
			Iterator iter = listeners.iterator( );
			while ( iter.hasNext( ) )
			{
				ActivityStackListener listener = ( (ActivityStackListener) iter