yet another nvidia question - multiscreen

[Karl Auer]

I have looked around and can't find quite this problem, nor a solution
to it:

I have NVidia hardware, a GeForce 9600M GS in a laptop. I'm running
Ubuntu 12.04, on x86064 hardware. The Nvidia driver is 295.40. The
NVidia settings application tells me it is using NV-CONTROL 1.27, but I
don't know what that is.

Here's the problem:

In previous versions of Ubuntu, most recently 10.4, I could use the
NVidia application to swicth an attached second screen into TwinView
mode. This was great for running presentations, because I got to keep my
usual screen on the laptop, and put the presentation on the external
screen. When I do this now, no matter what I do everything on the laptop
screen moves over to the external screen, leaving a blank laptop screen
(just background). Choosing to place the second screen above, below,
left or right of the laptop screen makes no difference, except that the
mouse cursor moves off a different edge between screens. I can slide
windows across to the blank screen, which is good and what I expected at
least that works as before.

I tried configuring a separate X screen, and the same thing happened
except that the laptop screen was white (not my background colour) and
although the mouse could be moved onto it, nothing else could. I was at
a loss to get anything started on the second X screen. Anything I
started on the one screen I could see (the external one) had two taskbar
items, which was weird. I'm running Gnome3, and with a second X screen,
it seemed to revert to GNOME2, unbidden!

Am I missing something obvious here? It worked before, doesn't work now.
The only thing really wrong is that with TwinView the external screen
takes precedence and become the main screen, regardless of what I do.
The option "Make this the primary display for the X screen" makes no
difference that I can see.

Any ideas?

Regards, K.

PS: The default Ubuntu "Displays" settings app does not even see the
external screen.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://www.biplane.com.au/blog

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