code: function _makeFileMostRecent(paneId, file) {
          var index,
              entry,
              pane = _getPane(paneId);
  
          if (!_traversingFileList) {
              pane.makeViewMostRecent(file);
  
              index = _findFileInMRUList(pane.id, file);
  
              entry = _makeMRUListEntry(file, pane.id);
  
              if (index !== -1) {
                  _mruList.splice(index, 1);
              }
  
              if (_findFileInMRUList(pane.id, file) !== -1) {
                  console.log(file.fullPath + " duplicated in mru list");
              }
  
              // add it to the front of the list
              _mruList.unshift(entry);
          }
      }
docs: Makes the file the most recent for the pane and the global mru lists
  @param {!string} paneId - id of the pane to mae th file most recent or ACTIVE_PANE
  @param {!File} file - File object to make most recent
  @private