code: function _documentSelectionFocusChange() {
          var curFullPath = MainViewManager.getCurrentlyViewedPath(MainViewManager.ACTIVE_PANE);
          if (curFullPath && _hasFileSelectionFocus()) {
              actionCreator.setSelected(curFullPath, true);
          } else {
              actionCreator.setSelected(null);
          }
          _fileViewControllerChange();
      }
docs: @private
  
  Handler for changes in document selection.