code: function initializeCommands() {
          var prefs = getPreferences();
  
          CommandManager.register(Strings.CMD_FILE_CLOSE_BELOW, closeBelow, function () {
              handleClose(closeBelow);
          });
          CommandManager.register(Strings.CMD_FILE_CLOSE_OTHERS, closeOthers, function () {
              handleClose(closeOthers);
          });
          CommandManager.register(Strings.CMD_FILE_CLOSE_ABOVE, closeAbove, function () {
              handleClose(closeAbove);
          });
  
          if (prefs.closeBelow) {
              workingSetListCmenu.addMenuItem(closeBelow, "", Menus.AFTER, Commands.FILE_CLOSE);
          }
          if (prefs.closeOthers) {
              workingSetListCmenu.addMenuItem(closeOthers, "", Menus.AFTER, Commands.FILE_CLOSE);
          }
          if (prefs.closeAbove) {
              workingSetListCmenu.addMenuItem(closeAbove, "", Menus.AFTER, Commands.FILE_CLOSE);
          }
          menuEntriesShown = prefs;
      }
docs: Register the Commands and add the Menu Items, if required