docs: protected void setupLogFile() throws IOException {
          String filename = System.getProperty("java.io.tmpdir") + File.separator + "fxlauncher.log";
          if (getParameters().getNamed().containsKey("logfile"))
              filename = getParameters().getNamed().get("logfile");
          System.out.println("logging to " + filename);
          FileHandler handler = new FileHandler(filename);
          handler.setFormatter(new SimpleFormatter());
          log.addHandler(handler);
      }