I sent steve jobs ([email protected]) an email saying that MacOS should have an unspoofable dialog for the system password authorization, same way they have for DRM videos etc. I also suggested the user could choose a secret phrase or image to be displayed in the dialog during system setup. Never heard back. This was when Steve was alive and in charge. And to this day anyone can spoof the system password dialog and steal the system password…
Sorry, I mean the current implementation seems trivial to spoof. I agree that doing something like your suggestion would make me feel much more comfortable about those logins.