Great utility and thank you for not making this spyware/malware!
May I make some suggestions? I would love if you included the following features:

1) I often miss the notification because it's so small, would be great if you can give users the options to make the pupup dialog center-screen and big.
2) allow to set the time between notifications.
3) allow to dismiss the notification via ESC button or quick mouse gesture.
4) show a counter until the notification is dismissed and allow to program that length.