To fix the original issue (to get any picture at all on the external display) I just installed restricted nvidia driver and then uninstalled it, both using the System>Administration>Hardware Drivers dialog.
To fox the other problem: to get picture on both internal and external display, I followed the description in bug #220563. Regards, Dag -- screen resolution dialog couldn't enable external display https://bugs.launchpad.net/bugs/223798 You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-control-center in ubuntu. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs