code: function _handleOpenDocumentsChanged(all, opened) {
          var open = opened || all;
  
          open.forEach(function (id) {
              _documentManager.getDocument(id).done(function (document) {
                  document.on("generatorSettings", _handleDocGeneratorSettingsChange.bind(undefined, id));
              }, function (error) {
                  _logger.warning("Error getting document during a document changed event, " +
                      "document was likely closed.", error);
              });
          });
      }
docs: Handler for a the "openDocumentsChanged" event emitted by the DocumentManager.
  Registers a generatorSettings change to update the StateManager appropiately
  
  @private
  @param {Array.<number>} all The complete set of open document IDs
  @param {Array.<number>=} opened The set of newly opened document IDs