code: def update_channels(self):
          
          group_dict = {k['name']: i for i, k in enumerate(self.groups)}
          group_index = group_dict[self.idx_group.currentText()]
          self.one_grp = self.groups[group_index]
  
          self.idx_chan.clear()
  
          self.idx_chan.setSelectionMode(QAbstractItemView.ExtendedSelection)
          for chan in self.one_grp['chan_to_plot']:
              name = chan + '—(' + '+'.join(self.one_grp['ref_chan']) + ')'
              item = QListWidgetItem(name)
              self.idx_chan.addItem(item)
docs: Update the channels list when a new group is selected.