Re: Solaris 10 X86, 6600, DualHead: Login-Screen moved halfway across the 2 screens .
Option "NoTwinViewXineramaInfo" "1" was missing !
Just found it in another thread of this solaris forum.
So: its not the Login-Screen sitting "between the two monitors" ... this is still the case !
Everything works nicely now, as expected.
(I hoped, that only one small bit was missing, since, when starting X,
the NVIDIA logo displayed OK streched across both screens, and
briefly, the old-fashioned X hourglass-mousepointer was there on an empty screen,
and it could be moved OK across both screens (if you are fast enough))
Just after that, X gave up and the Login-Screen re-appeared.
Anyway, also: Thank you NVIDIA Team at CeBIT computer fair 2006,
who told me to check this special forum for solaris only,
which is a great thing also.