Separate X Screens - possible on Intel Integrated HD Graphics?

[Simon Lees]

On 01/19/2016 12:59 AM, Simon McVittie wrote:
> On 17/01/16 16:49, Ken Taylor wrote:
>> On 01/17/2016 10:05 AM, rhkramer at gmail.com wrote:
>>> On Sunday, January 17, 2016 08:10:38 AM [Michal] wrote:
>>>> The usual pattern is that people ask about multiple screens but do not
>>>> really want them. Having multiple screens only limits what you can do
>>>> and gives you no meaningful benefits.
>>> On some of the industrial (process control) systems I've been
>>> responsible for,
>>> we put up to 4 monitors (with different displays) driven by one
>>> computer in
>>> front of a single operator.
> Multiple heads/outputs/monitors do not have to imply multiple X11
> 'screens'. They can, but they don't have to, and it's very rare to
> prefer multiple screens.
>
> 'Screen' is a jargon term in this context, like 'display' - I'm putting
> it in quotes to be unambiguous. If all your applications run with
> DISPLAY=:0, or equivalently DISPLAY=:0.0, you have one X11 'screen',
> potentially outputting to multiple monitors. If some of your
> applications run with DISPLAY=:0.1 and are permanently tied to a
> different set of monitors (probably a set of size 1), *that* is a second
> X11 'screen'.
>
> If you have multiple LCD/CRT/whatever monitors on one desk, or a laptop
> and a monitor, or a laptop and a projector, the option that is usually
> preferred is a single X11 'screen' spanning multiple monitors, with
> optional runtime switching between mirroring (same content on each
> output) and non-mirroring (different content on each output). That's
> what Xrandr normally does on modern systems, and as far as I'm aware,
> what all current desktop environments optimize for. It's also the X11
> equivalent of all the supported arrangements in Windows and OS X.
>
> For instance, on the laptop where I'm typing this (with Intel HD
> graphics, as it happens), here's what my output looks like:
>
> |----------|
> | monitor  ||--------|
> |          || laptop |
> |----------||--------|
>
> DISPLAY :0 --- screen :0.0 /-- HDMI2 --- monitor
>                             \-- LVDS1 --- laptop
>
> The equivalent with multiple 'screens':
>
> DISPLAY :0 /-- screen :0.0 --- HDMI2 --- monitor
>             \-- screen :0.1 --- LVDS1 --- laptop
>
> would mean I wouldn't be able to drag windows to and from the laptop, or
> copy and paste between the two screens, and I don't have enough
> historical X11 knowledge to know whether I'd need a second keyboard and
> mouse for that setup.
>
I used to do this with gnome 2 using nvidia's --separate-x-screen 
option, it didn't require a second keyboard and mouse. The reason I used 
to do this is so that I could change virtual desktops / workspaces 
independently per screen, ie screen 1 was on virtual desktop 3 and 
screen 2 was on virtual desktop 4, I could then change screen 2 to be on 
virtual desktop 1 without effecting screen 1. I found this more useful 
then being able to drag windows between screens. Unfortunately modern 
DE's often don't support this well as it involves running two instances 
of the display manager at the same time. In my case I found that 
enlightenment has this behavior without running separate x screens so I 
use that instead now.

Cheers
Simon