5 ms·

This is pretty cool - especially that it's at the point where it can be used with a real window manager. I'm curious why multiple screens is considered legacy

This is pretty cool - especially that it's at the point where it can be used with a real window manager. I'm curious why multiple screens is considered legacy baggage and thus out of scope, given how common multiple monitor setups are these days. I also have zero familiarity with X internals, so don't know if multiple monitor support is a horror show that'd be miserable to support.

kwhat4 4mo ago
Probably because Xinerama[1] and then later RandR[2] were an afterthought. [1] https://en.wikipedia.org/wiki/Xinerama https://en.wikipedia.org/wiki/Xinerama [2] https://xorg.freedesktop.org/archive/X11R7.5/doc/man/man1/xrandr.1.html https://xorg.freedesktop.org/archive/X11R7.5/doc/man/man1/xr...
chadgpt3 4mo ago
X screens are legacy. It used to be you could connect to a particular screen by number to open windows on that screen but the modern way to do it is to have one big virtual screen. X screens were like having a separate X server for each monitor, but with a single shared cursor and shared VRAM. You can see why that's an obsolete model.
- simmonmt 4mo ago
  Yep. When did virtual screens come in? My last full time experience with X was with Xsun in the early 2000s under Solaris. There was a shared cursor, I thought you could drag windows between monitors, but I also thought the DISPLAY variable was different for each (though I could be misremembering)
  - Liskni_si 4mo ago
    2007 is when xrandr 1.2 came and made it feasible to use on a laptop - enable/disable outputs dynamically without restarting X. Xinerama (the extension that enables one virtual screen over multiple outputs) existed before but the layout could only be defined statically - so you'd need to restart your X server with a different config if you wanted to connect a monitor or a projector or something.
  - rwmj 4mo ago
    $DISPLAY is definitely different for each X11 screen, ie. :0.0 for the first screen, :0.1 for the second and so on. (:1, :2 is used for more instances of the X11 server). I can't recall any application able to use multiple X11 screens (except in the trivial sense that you could set DISPLAY when starting the application), and I've been using X11 since X11R4.
- rixed 4mo ago
  Please do not see any malice in this naive question, but why is that an obsolete model? Back in the days I had very different displays that I could use to display various windows of a flight simulator (some dedicated to some instruments, the big one for the front view, for instance) and it was quite nice. It sounds like that would not be easy to replicate with a single shared frame buffer, but maybe I'm wrong (I've been using nothing but a small laptop screen for decades)
  - chadgpt3 4mo ago
    It's much easier to place a window at a specific position on a large frame buffer than to drag a window between screens when they are separate display servers.
deleted 4mo ago
[deleted]
somat 4mo ago
I suspect(with out reading the source to find out) that screens are the traditional X11 screens as opposed to the modern xrandr combined screen. Traditionally each screen in an X11 setup was it's own separate thing with it's own separate frame buffer. While technically applications could move between screens, this depended on the application caring enough to do so. It had to maintain two(or more) mirrored windows(one per screen) and keep them all aligned. So realistically no application did this. The modern method of doing multi monitors on X11 involves one large virtual screen with each monitor assigned a section of it. This has downsides, for example; this is where the myth that X11 can't do mixed DPI setups comes from. But it has one huge massive overwhelming upside. The application does not have to be aware that there are multiple screens and multi monitor setups just work.
- ltrever 4mo ago
  Can you pls share smt on how to properly do multi dpi in X? It is hard to find and I struggle with it
  - ndiddy 4mo ago
    The mixed DPI support on X11 is just that each monitor provides a DPI attribute that applications can query. It's up to the application or the toolkit it uses to actually look at this attribute and scale itself properly. In practice, this means that only Qt software will have DPI awareness on multi-monitor setups, and it requires having the "QT_AUTO_SCREEN_SCALE_FACTOR=1" environment variable set for applications that don't explicitly opt into it. What most X11 users actually do is set the global DPI to that of the highest DPI monitor, and use xrandr to scale down the framebuffer of the lower DPI monitor, which "zooms it out". Note that this has performance and image quality implications. There's a guide on how to do this here: https://blog.summercat.com/configuring-mixed-dpi-monitors-with-xrandr.html https://blog.summercat.com/configuring-mixed-dpi-monitors-wi...
    - somat 4mo ago
      The irony is that despite the myth to the contrary wayland does not even try to handle mixed DPI at all and only fakes it via the fractional scale hack and X11 has supported mixed DPI from probably day one. Admittedly X11 mixed DPI was using separate screens which were awkward to deal with and early versions of the unified screen tech (xinarama and xrandr) did not support mixed DPI. And even modern X11 while it provides the needed DPI information requires the application to care enough to support it. Which really means unless the toolkit provides it for free most applications are not going to do anything,

kwhat4 4mo ago

Probably because Xinerama[1] and then later RandR[2] were an afterthought. [1] https://en.wikipedia.org/wiki/Xinerama https://en.wikipedia.org/wiki/Xinerama [2] https://xorg.freedesktop.org/archive/X11R7.5/doc/man/man1/xrandr.1.html https://xorg.freedesktop.org/archive/X11R7.5/doc/man/man1/xr...

chadgpt3 4mo ago

X screens are legacy. It used to be you could connect to a particular screen by number to open windows on that screen but the modern way to do it is to have one big virtual screen. X screens were like having a separate X server for each monitor, but with a single shared cursor and shared VRAM. You can see why that's an obsolete model.

simmonmt 4mo ago
Yep. When did virtual screens come in? My last full time experience with X was with Xsun in the early 2000s under Solaris. There was a shared cursor, I thought you could drag windows between monitors, but I also thought the DISPLAY variable was different for each (though I could be misremembering)
- Liskni_si 4mo ago
  2007 is when xrandr 1.2 came and made it feasible to use on a laptop - enable/disable outputs dynamically without restarting X. Xinerama (the extension that enables one virtual screen over multiple outputs) existed before but the layout could only be defined statically - so you'd need to restart your X server with a different config if you wanted to connect a monitor or a projector or something.
- rwmj 4mo ago
  $DISPLAY is definitely different for each X11 screen, ie. :0.0 for the first screen, :0.1 for the second and so on. (:1, :2 is used for more instances of the X11 server). I can't recall any application able to use multiple X11 screens (except in the trivial sense that you could set DISPLAY when starting the application), and I've been using X11 since X11R4.
rixed 4mo ago
Please do not see any malice in this naive question, but why is that an obsolete model? Back in the days I had very different displays that I could use to display various windows of a flight simulator (some dedicated to some instruments, the big one for the front view, for instance) and it was quite nice. It sounds like that would not be easy to replicate with a single shared frame buffer, but maybe I'm wrong (I've been using nothing but a small laptop screen for decades)
- chadgpt3 4mo ago
  It's much easier to place a window at a specific position on a large frame buffer than to drag a window between screens when they are separate display servers.

deleted 4mo ago

[deleted]

somat 4mo ago

I suspect(with out reading the source to find out) that screens are the traditional X11 screens as opposed to the modern xrandr combined screen. Traditionally each screen in an X11 setup was it's own separate thing with it's own separate frame buffer. While technically applications could move between screens, this depended on the application caring enough to do so. It had to maintain two(or more) mirrored windows(one per screen) and keep them all aligned. So realistically no application did this. The modern method of doing multi monitors on X11 involves one large virtual screen with each monitor assigned a section of it. This has downsides, for example; this is where the myth that X11 can't do mixed DPI setups comes from. But it has one huge massive overwhelming upside. The application does not have to be aware that there are multiple screens and multi monitor setups just work.

ltrever 4mo ago
Can you pls share smt on how to properly do multi dpi in X? It is hard to find and I struggle with it
- ndiddy 4mo ago
  The mixed DPI support on X11 is just that each monitor provides a DPI attribute that applications can query. It's up to the application or the toolkit it uses to actually look at this attribute and scale itself properly. In practice, this means that only Qt software will have DPI awareness on multi-monitor setups, and it requires having the "QT_AUTO_SCREEN_SCALE_FACTOR=1" environment variable set for applications that don't explicitly opt into it. What most X11 users actually do is set the global DPI to that of the highest DPI monitor, and use xrandr to scale down the framebuffer of the lower DPI monitor, which "zooms it out". Note that this has performance and image quality implications. There's a guide on how to do this here: https://blog.summercat.com/configuring-mixed-dpi-monitors-with-xrandr.html https://blog.summercat.com/configuring-mixed-dpi-monitors-wi...
  - somat 4mo ago
    The irony is that despite the myth to the contrary wayland does not even try to handle mixed DPI at all and only fakes it via the fractional scale hack and X11 has supported mixed DPI from probably day one. Admittedly X11 mixed DPI was using separate screens which were awkward to deal with and early versions of the unified screen tech (xinarama and xrandr) did not support mixed DPI. And even modern X11 while it provides the needed DPI information requires the application to care enough to support it. Which really means unless the toolkit provides it for free most applications are not going to do anything,