docs: def on_btn_convert_3(self, event):
          """
          Open dialog for rough conversion of
          2.5 files to 3.0 files.
          Offer link to earthref for proper upgrade.
          """
          dia = pw.UpgradeDialog(None)
          dia.Center()
          res = dia.ShowModal()
          if res == wx.ID_CANCEL:
              webbrowser.open("https://www2.earthref.org/MagIC/upgrade", new=2)
              return
          ## more nicely styled way, but doesn't link to earthref
          #msg = "This tool is meant for relatively simple upgrades (for instance, a measurement file, a sample file, and a criteria file).\nIf you have a more complex contribution to upgrade, and you want maximum accuracy, use the upgrade tool at https://www2.earthref.org/MagIC/upgrade.\n\nDo you want to continue?"
          #result = pw.warning_with_override(msg)
          #if result == wx.ID_NO:
              #webbrowser.open("https://www2.earthref.org/MagIC/upgrade", new=2)
              #return
          # turn files from 2.5 --> 3.0 (rough translation)
          meas, upgraded, no_upgrade = pmag.convert_directory_2_to_3('magic_measurements.txt',
                                                                     input_dir=self.WD, output_dir=self.WD,
                                                                     data_model=self.contribution.data_model)
          if not meas:
              wx.MessageBox('2.5 --> 3.0 failed. Do you have a magic_measurements.txt file in your working directory?',
                            'Info', wx.OK | wx.ICON_INFORMATION)
              return
  
          # create a contribution
          self.contribution = cb.Contribution(self.WD)
          # make skeleton files with specimen, sample, site, location data
          self.contribution.propagate_measurement_info()
          # pop up
          upgraded_string = ", ".join(upgraded)
          if no_upgrade:
              no_upgrade_string = ", ".join(no_upgrade)
              msg = '2.5 --> 3.0 translation completed!\n\nThese 3.0 format files were created: {}.\n\nHowever, these 2.5 format files could not be upgraded: {}.\n\nTo convert all 2.5 files, use the MagIC upgrade tool: https://www2.earthref.org/MagIC/upgrade\n'.format(upgraded_string, no_upgrade_string)
              if 'criteria.txt' in upgraded:
                  msg += '\nNote: Please check your criteria file for completeness and accuracy, as not all 2.5 files will be fully upgraded.'
              if 'pmag_criteria.txt' in no_upgrade:
                  msg += '\nNote: Not all criteria files can be upgraded, even on the MagIC site.  You may need to recreate an old pmag_criteria file from scratch in Thellier GUI or Demag GUI.'
              wx.MessageBox(msg, 'Warning', wx.OK | wx.ICON_INFORMATION)
          else:
              msg = '2.5 --> 3.0 translation completed!\nThese files were converted: {}'.format(upgraded_string)
              wx.MessageBox(msg, 'Info', wx.OK | wx.ICON_INFORMATION)