Is it possible to force a monitor to stay in the server layout?

[Aaron Plattner]

On 12/21/12 06:29, Sven Berkvens-Matthijsse wrote:
> Hello,
>
> I can't seem to find an answer to my question anywhere on the web.
> Either my use case is weird, or I'm not searching correctly :-)
>
> I have X.org server 1.11.3 running on Ubuntu. I'm using the radeon
> driver with a Radeon HD6450. I have three monitors connected to the card
> (all three monitors have a DVI input), and I've set up the server to
> have all three monitors in one large desktop. This works brilliantly!
>
> Sometimes, I need to connect one of the monitors to another PC or other
> equipment with a HDMI or DVI output. My problem is that if I pull out
> one of the cables that is connected to the HD6450, that the card (and
> the X server) will detect that the monitor has been disconnected from
> the card. Consequently, the desktop size is modified and all my Gnome
> panels will be jumbled. If I reconnect the monitor, it comes back
> online, but the positioning of the windows and panels is not restored to
> what it used to be.

It's the X clients' job to effect that sort of policy.  In your case, 
it's probably gnome-settings-daemon.  You could try killing it as an 
experiment to see if the behavior goes away, or logging into a simpler 
desktop environment like Fluxbox that doesn't have a monitor policy daemon.

I don't know offhand if gnome-settings-daemon has an option to turn off 
automatic reconfiguration of the screens.

> What I would like is to be able to tell the X server that I don't care
> whether monitors are disconnected or not, and that it should keep the
> desktop size fixed, no matter which monitors are connected. My X
> configuration file includes a full server layout section, and also
> contains the resolutions of the monitors. Therefor, it should be
> possible, I guess, I just don't know how. Perhaps the current software
> is not able to handle this specific situation. I can live with it if the
> monitors need to be connected at the time that the X server starts. As
> long as I can disconnect them later on without the server layout and
> desktop size changing.

The nvidia driver has a "UseHotplugEvents" option you can use to 
suppress the RandR events that clients like gnome-settings-daemon listen 
for, to work around this sort of problem.  Maybe the radeon driver has 
something similar?

--
Aaron

> I realize that most people want the behavior that the X server exhibits
> currently, because in their case it will probably be an external monitor
> that is connected to a laptop on occasion. So I probably want something
> odd :-)
>
> Any help or pointers will be greatly appreciated. If the software is
> currently not capable of what I've attempted to describe, I'd also like
> to know, of course.


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