Laptop with EXternal TFT Monitor

Hi.

I'm having a problem with a dual display system with windows opening in
flaky locations.

I have a Clevo M7U laptop with a nVidia GeForce Go 7900 GTX adaptor,
running the 8.4.2.6 version of the driver. The laptop screen resolution
is 1920 x 1200, but running at 1280 x 768. I have it configured for a
dual monitor display with a 1440 x 900 17" TFT Monitor (Chimei CMV 938D).

The nView Desktop Manager is set to dual view, with windows able to span
displays (tried them with the other setting, no difference), opening
applications on the external display, repositioning dialogue boxes to
the cursor's display and not Snapping window edges. But some
applications still open on the laptop display, as do most dialogue
boxes. Many applications when full screened span 20 or so pixels into
the other display, which can only be fixed by changing the Snap window
edges setting to something different - doesn't seem to matter much what.
Very annoying behaviour.

Can anyone suggest a solution?

Edwin