docs: function addonsManager_setCategoryById(aSpec) {
      var spec = aSpec || { };
      var id = spec.id;
      var waitFor = (spec.waitFor == undefined) ? true : spec.waitFor;
  
      if (!id)
        throw new Error(arguments.callee.name + ": Category ID not specified.");
  
      // Retrieve the category and set it as active
      var category = this.getCategoryById({id: id});
      if (category)
        this.setCategory({category: category, waitFor: waitFor});
      else
        throw new Error(arguments.callee.name + ": Category '" + id + " not found.");
    }