code: def update_nseg(self):
          
          self.nseg = 0
          if self.one_grp:
              segments = self.get_segments()
  
              if segments is not None:
                  self.nseg = len(segments)
                  self.show_nseg.setText('Number of segments: ' + str(self.nseg))
                  times = [t for seg in segments for t in seg['times']]
                  self.parent.overview.mark_poi(times)
  
              else:
                  self.show_nseg.setText('No valid segments')
  
          self.toggle_freq()
docs: Update the number of segments, displayed in the dialog.