Zooms grid columns

def _zoom_cols(self, zoom):
        """Zooms grid columns"""

        self.grid.SetDefaultColSize(self.grid.std_col_size * zoom,
                                    resizeExistingCols=True)
        self.grid.SetColLabelSize(self.grid.col_label_size * zoom)

        for col, tab in self.code_array.col_widths:
            if tab == self.grid.current_table and \
               col < self.grid.code_array.shape[1]:
                base_col_width = self.code_array.col_widths[(col, tab)]
                if base_col_width is None:
                    base_col_width = self.grid.GetDefaultColSize()
                zoomed_col_size = base_col_width * zoom
                self.grid.SetColSize(col, zoomed_col_size)