docs: def activate_state_tab(self, state_m):
          """Opens the tab for the specified state model
  
          The tab with the given state model is opened or set to foreground.
  
          :param state_m: The desired state model (the selected state)
          """
          # The current shown state differs from the desired one
          current_state_m = self.get_current_state_m()
          if current_state_m is not state_m:
              state_identifier = self.get_state_identifier(state_m)
  
              # The desired state is not open, yet
              if state_identifier not in self.tabs:
                  # add tab for desired state
                  page_id = self.add_state_editor(state_m)
                  self.view.notebook.set_current_page(page_id)
              # bring tab for desired state into foreground
              else:
                  page = self.tabs[state_identifier]['page']
                  page_id = self.view.notebook.page_num(page)
                  self.view.notebook.set_current_page(page_id)
  
          self.keep_only_sticked_and_selected_tabs()