docs: def model_changed(self, model, prop_name, info):
          """ Highlight buttons according actual execution status. Furthermore it triggers the label redraw of the active
          state machine.
          """
  
          # TODO: find nice solution
          # this in only required if the GUI is terminated via Ctrl+C signal
          if not self.view:
              # this means that the main window is currently under destruction
              return
  
          execution_engine = rafcon.core.singleton.state_machine_execution_engine
          label_string = str(execution_engine.status.execution_mode)
          label_string = label_string.replace("STATE_MACHINE_EXECUTION_STATUS.", "")
          self.view['execution_status_label'].set_text(label_string)
  
          current_execution_mode = execution_engine.status.execution_mode
          if current_execution_mode is StateMachineExecutionStatus.STARTED:
              self.view['step_buttons'].hide()
              self._set_single_button_active('button_start_shortcut')
          elif current_execution_mode is StateMachineExecutionStatus.PAUSED:
              self.view['step_buttons'].hide()
              self._set_single_button_active('button_pause_shortcut')
          elif execution_engine.finished_or_stopped():
              self.view['step_buttons'].hide()
              self._set_single_button_active('button_stop_shortcut')
          else:  # all step modes
              self.view['step_buttons'].show()
              self._set_single_button_active('button_step_mode_shortcut')