When I'm logged in with user X, lock my screen, switch to user Y, lock his screen, switch back to user X, I'm back at tty7. That's great. User Y is at tty8. Fine!
But when I log user X out, I expect to return to user Y, at tty8. But instead, the gdm login is shown at tty7.
This might seem far-fetched, or even logical to those who understand the underlying implementation. The user-switching thing offers really interesting usability possibilities, especially where families are using ubuntu.
But making user-switching as transparent as possible is quite important. Maybe there are other situations possible where the system doesn't work as expected, but it would be great to catch those too.
(if a developer that feels responsible sees this, please comment on how you prioritize this bug).
I created Bug #40011 a short while ago, which I believe is another situation where fast user switching leads to something that users will find unexpected (a blank tty).
The problem in Bug #40011 is a manifestation of the same problem as this bug. The user interface just follows the (invisible) underlying implementation, even when the underlying implementation leads to a black hole.