Description of problem: 1 monitor connected to on-board intel card (DP), 2 monitors connected to ATI radeon (dual DVI). xfce-display-settings pops up a dialog box "Unable to start the Xfce Display Settings" Version-Release number of selected component (if applicable): xfce4-settings-4.8.3-1.el6.x86_64
Multi monitor support is... not very existant in 4.8 sadly. Can you run xfce4-display-settings from a terminal and see if it provides any output?
(In reply to Kevin Fenzi from comment #1) > Multi monitor support is... not very existant in 4.8 sadly. > > Can you run xfce4-display-settings from a terminal and see if it provides > any output? It doesn't, I should've mentioned that. I took a brief look at strace, but it seems to get filled up with polling on the dialog box (?), nothing stood out to me. If it's relevan't, xrandr doesn't show all three "outputs" either: you have to run it with --screen 1 to see the intel-DP monitor or with --screen 2 to see radeon-DVI ones. Anyway, between Dell's BIOS complaining about unsupported configuration and workspaces and monitor rotation not working (as per my other bug), I'm disconnecting the 3rd screen. FWIW we have a couple of PCs with 3 outputs on single video card -- 3-monitor setup seems to work fine on those. It's the 2 different video cards that are problematic.
This is reported against 4.8.x . Closing.