def _plot_onscroll(event, params):
 if (event.key == 'control'):
  if (event.step < 0):
   event.key = '-'
  else:
   event.key = '+'
  _plot_onkey(event, params)
  return
 if params['butterfly']:
  return
 _plot_raw_onscroll(event, params, len(params['ch_names']))

def _plot_onscroll ( event , params ) : if ( event . key == 'control' ) : if ( event . step < 0 ) : event . key = '-' else : event . key = '+' _plot_onkey ( event , params ) return if params [ 'butterfly' ] : return _plot_raw_onscroll ( event , params , len ( params [ 'ch_names' ] ) )
handle scroll events .