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
commonProps.remove( propDefn );
					break;
				}
			}
		}
		return Collections.unmodifiableList( commonProps );
	}
	/**
	 * Returns the property definition list that has the minimum size.
	 * 
	 * @return the property definition list that has the minimum size.
	 */
	private List getMinPropDefns( )
	{
		int min = Integer.MAX_VALUE;
		List rtnPropDefns = Collections.EMPTY_LIST;
		for ( int j = 0; j < elements.size( ); j++ )
		{
			Object item = elements.get( j );
			if ( !( item instanceof DesignElementHandle ) )
				return Collections.EMPTY_LIST;
			List propDefns = ( (DesignElementHandle) item ).getElement( )
					.getPropertyDefns( );
			if ( propDefns.size( ) < min )
			{
				min = propDefns.size( );
				rtnPropDefns = propDefns;
			}
		}
		return rtnPropDefns;