code: def on_remove_cols(self, event):
          
          # open the help message
          self.toggle_help(event=None, mode='open')
          # first unselect any selected cols/cells
          self.remove_cols_mode = True
          self.grid.ClearSelection()
          self.remove_cols_button.SetLabel("end delete column mode")
          # change button to exit the delete columns mode
          self.Unbind(wx.EVT_BUTTON, self.remove_cols_button)
          self.Bind(wx.EVT_BUTTON, self.exit_col_remove_mode, self.remove_cols_button)
          # then disable all other buttons
          for btn in [self.add_cols_button, self.remove_row_button, self.add_many_rows_button]:
              btn.Disable()
          # then make some visual changes
          self.msg_text.SetLabel("Remove grid columns: click on a column header to delete it.  Required headers for {}s may not be deleted.".format(self.grid_type))
          self.help_msg_boxsizer.Fit(self.help_msg_boxsizer.GetStaticBox())
          self.main_sizer.Fit(self)
          self.grid.SetWindowStyle(wx.DOUBLE_BORDER)
          self.grid_box.GetStaticBox().SetWindowStyle(wx.DOUBLE_BORDER)
          self.grid.Refresh()
          self.main_sizer.Fit(self) # might not need this one
          self.grid.changes = set(range(self.grid.GetNumberRows()))
docs: enter 'remove columns' mode