code: function _handleWorkingSetMove(event, file, sourcePaneId, destinationPaneId) {
          // Check existing list for this doc path and source pane entry
          var index = _.findIndex(_mrofList, function (record) {
              return (record && record.file === file.fullPath && record.paneId === sourcePaneId);
          }), tIndex;
          // If an entry is found update the pane info
          if (index >= 0) {
              // But an entry with the target pane Id should not exist
              tIndex = _.findIndex(_mrofList, function (record) {
                  return (record && record.file === file.fullPath && record.paneId === destinationPaneId);
              });
              if (tIndex === -1) {
                  _mrofList[index].paneId = destinationPaneId;
              } else {
                  // Remove this entry as it has been moved.
                  _mrofList.splice(index, 1);
              }
          }
      }
docs: To update existing entry if a move has happened