code: def update(self):
          
          self.idx_chan.clear()
          for chan_name in self.parent.traces.chan:
              self.idx_chan.addItem(chan_name)
  
          if self.selected_chan is not None:
              self.idx_chan.setCurrentIndex(self.selected_chan)
              self.selected_chan = None
docs: Add channel names to the combobox.