code: def select_idle_worker(self, ctrl, shift):
      
      action = sc_pb.Action()
      mod = sc_ui.ActionSelectIdleWorker
      if ctrl:
        select_worker = mod.AddAll if shift else mod.All
      else:
        select_worker = mod.Add if shift else mod.Set
      action.action_ui.select_idle_worker.type = select_worker
      return action
docs: Select an idle worker.