thanks for reporting this.

I'll try to reproduce this with my good old iBook (the only Mac I 
have a video adapter for). As far as I can recall, it worked nicely 
on that one the last time I tried.

How long does OS X need on your machine to switch from the normal to 
the new resolution?

(background is that - iirc - OS X notifies applications of resolution 
changes immediately, but it will not supply them with the new 
resolution info right away, but only after it has switched to it - 
which makes the whole "adapt position to new resolution"- 
functionality a timing problem)

And does closing and reopening the menu rectify the problem?

Best regards, 
Felix