// mainJar can also be a directory
sbool standalone_start(S[] args, S programName, File newUserDir, File mainJar, File unpackDir, S framesID) {
  System.out.println(programName + " starting.");
  ret true if javaXStandalone_init(args);
  if (newUserDir != null) setUserDir(newUserDir);
  ret true if standalone_activateFrames(framesID);
  vm_setResourceLoader(resourceLoaderFromJarOrDir(mainJar, unpackDir));
  print("Resource loader installed (" + f2s(mainJar) + " => " + f2s(unpackDir) + ")");
  false;
}