code: function addonsManager_addons(aSpec) {
      var spec = aSpec || {};
  
      return this.getElements({
        type: "addons",
        subtype: spec.attribute,
        value: spec.value,
        parent: this.selectedView
      });
    }
docs: Returns the addons from the currently selected view which match the
  filter criteria
  
  @param {object} aSpec
  Information about the filter to apply
  Elements: attribute - DOM attribute of the wanted addon
  [optional - default: ""]
  value     - Value of the DOM attribute
  [optional - default: ""]
  
  @returns List of addons
  @type {array of ElemBase}