F18 doesn't see full laptop screen resolution

[Per Bothner]

[Officially off-topic, as this is a problem with Fedora 18, not testing.
I'm afraid I didn't get a chance to try out F18 before it was released.
Next time ...]

I have a major F18 regression, which makes it unusable: The Gnome/X11
environment sets the screen resolution 10 1280x1024 - but the actual
resolution is 1920x1080.   Also, an external display is not seen, even when
I click "Detect Displays" in the "Displays" portion of System Settings.

This is vanilla Gnome 3.  (I assume KDE wouldn't make a difference, though
I'm willing to try it.) This is, alas, an "Optimus" laptop: a GeForce GT 
555M,
along with Intel Sandybridge Mobile GT2+.  Also alas: There is no way to 
disable
the Nvidia chip by booting into the BIOS settings.

F18 was installed from scratch, so I may have missed installing or
setting something.

So for now I'm stuck on Fedora 17 or running Fedora 18 under VirtualBox
under Windows - neither of which makes me happy.  Please save me from this
unpleasant choice!  What do I look for to fix this?
-- 
	--Per Bothner
per at bothner.com   http://per.bothner.com/