void loop() {
  ABWindow *window;
  bool focused;

  // pause render until it's time for the next frame
  if (!(arduboy.nextFrame()))
    return;

  arduboy.clear();

  // we set our cursor 5 pixels to the right and 10 down from the top
  // (positions start at 0, 0)
  // arduboy.setCursor(4, 9);

  // then we print to screen what is in the Quotation marks ""
  // arduboy.print(F("Hello, world!"));


  app.tick();

  // z-indexing
  for (int8_t z=-1; z<10; z++) {
    for (uint8_t w=0; w < MAX_WINDOWS; w++) {
      window = &app.windows[w];
      if (window->zIndex == z && window->live()) {
        // we need to save the focus state because the event handler
        // could change it out from under us
        focused = window->focused;
        // only the focused window receives access to button state
        if (!focused) { app.pushButtons(); }
        if (window->eventHandler != NULL) {
          window->eventHandler(TICK_EVENT);
        }
        window->renderHandler();
        // we pop after render so render does not have "secret" knowledge
        // of buttons that the event handler does not have access to
        if (!focused) { app.popButtons(); }
      }
    }
  }


  arduboy.setCursor(0,0);
  // then we finaly we tell the arduboy to display what we just wrote to the display
  arduboy.display();
}