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
{
		List list = getCommonProperties( );
		final List visibleList = new ArrayList( );
		for ( int i = 0; i < list.size( ); i++ )
		{
			IElementPropertyDefn propDefn = (IElementPropertyDefn) list.get( i );
			if ( isPropertyVisible( propDefn.getName( ) ) )
			{
				visibleList.add( propDefn );
			}
		}
		return new GroupPropertyIterator( visibleList );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#isPropertyVisible(java.lang.String)
	 */
	protected boolean isPropertyVisible( String propName )
	{
		List elements = getElements( );
		for ( int i = 0; i < elements.size( ); i++ )
		{
			PropertyHandle propertyHandle = ( (DesignElementHandle) elements
					.get( i ) ).getPropertyHandle( propName );
			
			
			
			if ( propertyHandle != null && !propertyHandle.isVisible( )
					|| propertyHandle == null )