svoid startPlatformFileManager(File dir) {
  S cmd = isWindows() ? "start"
    : isMac() ? "open"
    : isOnPATH("gio") ? "gio open"
    : firstCmdOnPATH_mandatory("xdg-open");
  cmd += pqO(dir);
  print("Starting platform file manager: " + cmd);
  //nohup(cnd);
  backtick(cmd);
  print("Platform file manager exited");
}