if ( obj instanceof ComputedColumnHandle )
if ( obj == dummyChoice && !existDefaultColumn( ) )
			public void selectionChanged( SelectionChangedEvent event )			{				// updateTableButtons( );				if ( !bindingTable.getSelection( ).isEmpty( ) )				{					Object obj = ( (IStructuredSelection) bindingTable.getSelection( ) ).getFirstElement( );					if ( obj instanceof ComputedColumnHandle )					{						ComputedColumnHandle column = (ComputedColumnHandle) obj;						BindingExpressionProvider provider = new BindingExpressionProvider( column.getElementHandle( ) );						provider.addFilter( new ComputedColumnExpressionFilter( bindingTable ) );						expressionCellEditor.setExpressionProvider( provider );					}				}			}