code: def init_login(self, from_local=False):
          
          if self.toolbar:
              self.removeToolBar(self.toolbar)
          widget_login = login.Loading(self.statusBar(), self.theory_main)
          self.centralWidget().addWidget(widget_login)
          widget_login.loaded.connect(self.init_tabs)
          widget_login.canceled.connect(self._quit)
          widget_login.updated.connect(self.on_update_at_launch)
          if from_local:
              widget_login.propose_load_local()
          else:
              self.statusBar().showMessage("Données chargées depuis le serveur.", 5000)
docs: Display login screen. May ask for local data loading if from_local is True.