Loads the column information for this tree widget for the given record.
        
        :param      record      | <orb.Table>
                    columnName  | <str>
                    value       | <variant>

def _loadColumns(self, record, columnName, value):
        """
        Loads the column information for this tree widget for the given record.
        
        :param      record      | <orb.Table>
                    columnName  | <str>
                    value       | <variant>
        """
        value = unwrapNone(value)
        item = self.findRecordItem(record)
        if item:
            item.updateColumnValue(record.schema().column(columnName),
                                   value,
                                   self.column(columnName))