* Desktop extended across two monitors when X-server starts (via gdm) (configured in xorg.conf). * Log in to xfce4 session * Xfce4 desktop started on one monitor only, the other blanked * xrandr shows two monitors connected * xfce4 settings "Display" shows one Screen * xfce4 settings "Desktop" shows one unnamed monitor * run 'xrandr --output LVDS1 --auto --left-of VGA1 --output VGA1 --auto' * both monitors come on, desktop is resized back across both, two panels are moved to their preferred place, everything working perfectly * xfce4 settings "Display" shows one Screen as before * xfce4 settings "Desktop" shows two monitors with correct names * kill xfce4-settings-helper and let the session manager(?) restart it * desktop reverts to one monitor again I can't see any way to configure xfce4-settings-helper to stop it messing with xrandr. However, when I DELETE the binary :-) everything does work as normal without monitors switching on and off. Note that a Gnome session also starts smoothly without changing the extended desktop, which is the behaviour I'd like from Xfce.
I have compiled a version with HAVE_XRANDR removed from config.c which prevents the calls in main.c to instantiate (and release) the displays helper object. Not a fix, obviously, but it prevents the undesirable behaviour - my monitors are unmolested.
Fixed in git master.