Dual monitors odd window behaviour

My dual monitor setup on openSUSE 13.2 is fundamentally working ok, I can plug in one to the VGA and another to the DVI outputs from the motherboard and get both working, configure via the Gnome panel and mostly ok from there; #1 / left / DVI is secondary and #2 / right / VGA is primary with the toolbar at the top. However some exceptions: when Libreoffice starts it places the splash screen correctly in the primary screen but then loads the default window in the secondary. If I drag the window over to the primary it will remember, but only for the current session. The most odd behaviour is when I have placed the secondary display in OFF mode, if I log out of the session from the primary screen, that screen goes dark and the login screen goes to the secondary which is off! I can repeat the behaviour with the display active and I see that is where the login screen appears.

So I can’t put the secondary in off mode; it has to remain active because just about anything can happen. I wonder if there is a checklist to set up the monitors to increase the predictability of these oddities?

I’m not familiar with gdm or its idiosyncrasies, so it may take the advice of a Gnome user to help resolve this, but I did find this Fedora thread, which may be relevant here. In particular, post#7…

I’ve “resolved” issue following some advice I found in the mailing-list (gdm-list?); namely, following the previously-mentioned resolution of copying monitors.xml file from “~/.config/monitors.xml” after I’ve turned off the second monitor. Once the second monitor is turned off in “Settings”>>“Displays”, the monitors.xml file is re-written to “~/.config/monitors.xml” to reflect the changed configuration. Then, copying over that file to “/var/lib/gdm/.config/” takes affect with gdm. Hope this helps someone else in this predicament.

I’m hoping that this helps you by creating the desired monitor configuration in /var/lib/gdm/.config/monitors.xml and the display manager will then display the login screen on the correct monitor.

Further discussions here concerning setting the primary monitor


I think it may have to do with responsiveness of the individual monitors. After observing the two monitors working it is clear that the one set as secondary is faster than the other. The system always marks it #1 presumably since it or the motherboard video port it is connected to is just that much more responsive, about half to a full second faster. If I arrange the monitors so that the fastest is the primary and #1 then the window behaviour is correct. So that is my working theory for now.

I think the default primary monitor comes down to the driver and display output. Swapping the physical arrangement of the monitors is one solution where practical to do so :slight_smile:

It can be configured via Xorg confg files as well, or at a DE level, which only kicks in later when the display manager starts.