code: function addonsManager_getCategoryById(aSpec) {
      var spec = aSpec || { };
      var id = spec.id;
  
      if (!id)
        throw new Error(arguments.callee.name + ": Category ID not specified.");
  
      return this.getCategories({
        attribute: "id",
        value: "category-" + id
      })[0];
    }
docs: Get the category element for the specified id
  
  @param {object} aSpec
  Information for getting a category
  Elements: id - Category id (search, discover, languages,
  searchengines, extensions, themes, plugins,
  availableUpdates, recentUpdates)
  
  @returns Category
  @type {ElemBase}