Bug 146761 All structure properties change can't be restore
Steps to reproduce: 1.New a report, extends lib.table 2.Add a structure property(such as filter, column binding...) on table 3.Choose the table, click "Restore Property" Expected result: Local propery is removed Actual result: Local property can't be removed so that "Restore Property" is always enabled
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/SimpleGroupElementHandle.java
* 
	 * @param moduleHandle
	 *            the handle of module
	 * @param elements
	 *            a list of handles of design elements. If a item is not
	 *            <code>DesignElementHandle</code>, it is ignored.
	 * @see DesignElementHandle
	 */
	public SimpleGroupElementHandle( ModuleHandle moduleHandle, List elements )
	{
		assert moduleHandle != null;
		module = moduleHandle.getModule( );
		assert elements != null;
		this.elements = elements;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#getElements()
	 */
	public List getElements( )
	{
		return elements;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#getModule()
	 */
	public Module getModule( )