[xjay]

I assumed the timer was there to prevent clicking Install by accident.

Popup dialogs may appear right "above" something else you were clicking on, or while you're typing; hitting Enter, or Escape, which then causes the dialog to eat the input and vanish.

Putting a dialog on cooldown like that would be interesting UX behavior. So if a dialog receives input < 1 sec after creation, it would discard the input and put itself on a cooldown timer, like that install dialog, or you could just change the context and avoid popups altoghether.

PS: I'd mark my post Off-Topic/Digression/UX if HN had that option.