  */
 void backlight_timeout(uint64_t timeout)
 {
+  if(backlight_on_time == -1)
+    return;
+
   uint64_t delta_t = millis() - backlight_on_time;
   if(delta_t > timeout)
   {

  return true;
}

uint64_t backlight_on_time;

/**
 * Sets the state of the backlight.

  {
    case DISPLAY_IDLE:
      if(handle_idle_buttons(id))
        set_backlight(BACKLIGHT_ON_TIMEOUT);
      break;

    case DISPLAY_NOTIFICATIONS:
      if(handle_notification_buttons(id))
        set_backlight(BACKLIGHT_ON_TIMEOUT);
      break;

    default:
