Felix Miata wrote:
> Clear as mud.
>
> Monitor = display. This is physical.
>
> Screen for X purposes is comprised of from 1 to N displays aka 1 to N
> monitors, and most often is. It's a logical construct in which displayed
> output can be either mirrored (cloned) or discrete (unique).
>
Not exactly - it utilizes the device and AFAIR if you have multihead GPU,
you could have more than one screens with more than one monitors and define
there whatever acceptable displays you can define.
X11 terminology is complex and bloated with 30 years old poorly named abstractions.
Especially funny is that term "display" has different meaning in xorg.conf (screen's width and depth) and X11 protocol (collection of screens: DISPLAY=display.screen)
Nowadays you should have:
* One screen and one display (DISPLAY=:0.0) unless you do something rare like Zaphod mode.
* Use randr (either directly or with tools provided by your DE) to configure each monitor as different output
RandR solves most issues. Other approaches are outdated: Xinerama requires manual configuration and doesn't support different resolutions without of "dead zones"
"Several screens" (original X solution) does not allow you to move windows between them (except several carefully written apps)