the nvidia xconfig utility finds and sets up my external display without any problems. It is set up as a separate screen- not twinview.

When I log in to Gnome, each screen is set up as an independent workspace. But when I log in to KDE, systemsettings tells me that I don't have the capability to use multiple monitors.

What could be the problem?

I have never been able to determine what the "Multiple Monitors" utility in System Settings actually does. Unless you are running KDE 4.3 or Trunk, I do not believe that spreading Workspaces across more than one screen works particularly well.

bcooksley wrote:I have never been able to determine what the "Multiple Monitors" utility in System Settings actually does. Unless you are running KDE 4.3 or Trunk, I do not believe that spreading Workspaces across more than one screen works particularly well.

I'm running 4.3 from Debian unstable

It is set up as a separate screen- not twinview.

Work is being worked on for the next minor release (4.4) to support this kind of support.

http://aseigo.blogspot.com/2009/07/multihead.html

Thanks. I'll have to try again when 4.4 make it into sid.