anchor.diff:    }
   }
   
  +/**
  + * The abstract parent class of Spark related actions.
  + */
   abstract class SparkAction extends Action {
     Spark spark;
   
  
positive.code:     defaultBinding("ctrl-o");
    }
  
    void invoke() {
      // TODO:
      spark.openFile(null);
    }
  }
  
  class FileSaveAction extends SparkAction {
  
negative.code:     defaultBinding("ctrl-n");
    }
  
    void invoke() => spark.newFile(null);
  }
  
  class FileOpenAction extends SparkAction {
  