def _ondim(self, dimension, valuestring):
        """Converts valuestring to int and assigns result to self.dim

        If there is an error (such as an empty valuestring) or if
        the value is < 1, the value 1 is assigned to self.dim

        Parameters
        ----------

        dimension: int
        \tDimension that is to be updated. Must be in [1:4]
        valuestring: string
        \t A string that can be converted to an int

        """

        try:
            self.dimensions[dimension] = int(valuestring)
        except ValueError:
            self.dimensions[dimension] = 1
            self.textctrls[dimension].SetValue(str(1))

        if self.dimensions[dimension] < 1:
            self.dimensions[dimension] = 1
            self.textctrls[dimension].SetValue(str(1))
Converts valuestring to int and assigns result to self.dim

        If there is an error (such as an empty valuestring) or if
        the value is < 1, the value 1 is assigned to self.dim

        Parameters
        ----------

        dimension: int
        \tDimension that is to be updated. Must be in [1:4]
        valuestring: string
        \t A string that can be converted to an int