On 17/01/16 16:49, Ken Taylor wrote: > On 01/17/2016 10:05 AM, rhkra...@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 have to admit that the Linux / X window (and successor) terminology >> confurses me--when I say multiple screens, I mean multiple monitors >> driven by >> a single PC and different content on each, and, ideally (but not >> always the >> case) the ability to move content between displays and copy and paste >> to and >> from each. It sounds as though rhkramer may be one of the people Michal is thinking of, who has been confused by the unfortunate historical terminology, does want multiple monitors, but does not necessarily want multiple of the historical X11 construct whose jargon term is 'screen'. > I appreciate the vote of confidence. Perhaps "separate X screens" is > something which only a small percentage of user are multi-tasking enough > to take advantage of. However, I am one of them. From other emails, it sounds as though you (for disambiguation: Ken) are one of the minority that genuinely does want multiple X11 'screens', with no copy/paste between them, and no ability to move windows between them. I'm not sure how this actually improves your experience when multi-tasking when compared with a Xrandr-style large 'screen' spanning multiple monitors, but "you asked for it/you got it"[1]. However, this is a sufficiently small minority that it seems reasonable to ask "are you *sure* this is really what you're looking for?" when someone asks for it, because it's fairly common for people who are confused by the terminology to think they want multiple (jargon) 'screens' for their multiple (non-jargon) screens, even though that leads to reduced functionality. If your goal is to have immovable displays appearing on particular monitors, that's also possible to achieve within a single 'screen' by modifying or configuring a window manager or compositor to place windows where you want them. (For instance, tiling window managers like Awesome[2] tend to support this sort of thing.) -- Simon McVittie Collabora Ltd. <http://www.collabora.com/> [1] the lesser-known opposite of WYSIWYG [2] http://awesome.naquadah.org/wiki/Using_Multiple_Screens _______________________________________________ xdg mailing list xdg@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/xdg