void pause () {
    synchronized (synch) {
      if (!running) return;
      running = false;
      pause = true;
      while (pause) {
        try {
          // TODO: fix deadlock race condition with quick resume/pause.
          // Temporary workaround:
          // Android ANR time is 5 seconds, so wait up to 4 seconds before assuming
          // deadlock and killing process. This can easily be triggered by opening the
          // Recent Apps list and then double-tapping the Recent Apps button with
          // ~500ms between taps.
          synch.wait(4000);
          if (pause) {
            // pause will never go false if onDrawFrame is never called by the GLThread
            // when entering this method, we MUST enforce continuous rendering
            Gdx.app.error(LOG_TAG, "waiting for pause synchronization took too long; assuming deadlock and killing");
            android.os.Process.killProcess(android.os.Process.myPid());
          }
        } catch (InterruptedException ignored) {
          Gdx.app.log(LOG_TAG, "waiting for pause synchronization failed!");
        }
      }
    }
  }

open class PatchedAndroidFragmentApplication : AndroidFragmentApplication() {
  private val exec = Executors.newSingleThreadExecutor()
  private val forcePause = Runnable {
    try {
      Thread.sleep(100)
    } catch (e: InterruptedException) {
    }
    graphics.onDrawFrame(null)
  }
  override fun onPause() {
    if (activity!!.window.attributes.flags and WindowManager.LayoutParams.FLAG_FULLSCREEN == WindowManager.LayoutParams.FLAG_FULLSCREEN) {
      // 是全屏
      exec.submit(forcePause)
    }
    super.onPause()
  }
}