code: def add_rollback_panels(self):
          
          from wagtailplus.utils.edit_handlers import add_panel_to_edit_handler
          from wagtailplus.wagtailrollbacks.edit_handlers import HistoryPanel
  
          for model in self.applicable_models:
              add_panel_to_edit_handler(model, HistoryPanel, _(u'History'))
docs: Adds rollback panel to applicable model class's edit handlers.