docs: def focus_notebook_page_of_controller(self, controller):
          """Puts the focus on the given child controller
  
          The method implements focus request of the notebooks in left side-bar of the main window. Thereby it is the
          master-function of focus pattern of the notebooks in left side-bar.
  
          Actual pattern is:
          * Execution-History is put to focus any time requested (request occur at the moment when the state-machine
          is started and stopped.
          * Modification-History one time focused while and one time after execution if requested.
  
          :param controller The controller which request to be focused.
          """
          # TODO think about to may substitute Controller- by View-objects it is may the better design
          if controller not in self.get_child_controllers():
              return
          # logger.info("focus controller {0}".format(controller))
          if not self.modification_history_was_focused and isinstance(controller, ModificationHistoryTreeController) and \
                  self.view is not None:
              self.view.bring_tab_to_the_top('history')
              self.modification_history_was_focused = True
  
          if self.view is not None and isinstance(controller, ExecutionHistoryTreeController):
              self.view.bring_tab_to_the_top('execution_history')
              self.modification_history_was_focused = False