Bug 147687 Assert err happened with design ui
Run BIRT in workbench with argument -ea. Assert err happened when using design ui to open a design file.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/command/WrapperCommandStack.java
/*************************************************************************************
 * Copyright (c) 2004 Actuate Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 * Actuate Corporation - Initial implementation.
 ************************************************************************************/
package org.eclipse.birt.report.designer.internal.ui.command;
import org.eclipse.birt.report.designer.core.model.SessionHandleAdapter;
import org.eclipse.birt.report.model.api.CommandStack;
import org.eclipse.birt.report.model.api.activity.ActivityStackListener;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.CommandStackListener;
/**
 * @author David Michonneau
 * 
 * This class is a command stack for the GEF framework. It internally access the
 * ActivityStack class of the DE. No commands are pushed to the command stack or
 * ActivityStack here since the Design handles take care of that when executed.
 * Commands are executed as transactions.
 */
public class WrapperCommandStack extends org.eclipse.gef.commands.CommandStack
{
	private CommandStack ar;
	public WrapperCommandStack( )
	{
		this( SessionHandleAdapter.getInstance( )