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/GroupPropertyHandle.java
return false;
		DesignElementHandle elemHandle = (DesignElementHandle) iter.next( );
		
		Object baseValue = null;
		if ( propDefn.getTypeCode( ) == IPropertyType.STRUCT_TYPE)
			baseValue = elemHandle.getProperty( propDefn.getName( ) );
		else
			baseValue = elemHandle.getStringProperty( propDefn.getName( ) );
		while ( iter.hasNext( ) )
		{
			elemHandle = (DesignElementHandle) iter.next( );
			Object value = null;
			if ( propDefn.getTypeCode( ) == IPropertyType.STRUCT_TYPE)
				value = elemHandle.getProperty( propDefn.getName( ) );
			else
				value = elemHandle.getStringProperty( propDefn.getName( ) );
			
			if ( baseValue == null )
			{
				if ( value != null )
					return false;
			}
			else
			{
				if ( !baseValue.equals( value ) )
					return false;
			}
		}
		return true;
	}