Assigns the order names for this tree based on the name of the
        columns.

def assignOrderNames(self):
        """
        Assigns the order names for this tree based on the name of the
        columns.
        """
        try:
            schema = self.tableType().schema()
        except AttributeError:
            return
        
        for colname in self.columns():
            column = schema.column(colname)
            if column:
                self.setColumnOrderName(colname, column.name())