(x-display-pixel-height)

[Perry Smith]

I’m using a Mac laptop and can plug in a second monitor.

I’m also using two instances of Emacs 28.1.  One I built on macOS with NextStep 
support.  The other I build on Free BSD with X11 Lucid.

I open the native macOS Emacs normally by double clicking the icon.  I open the 
Free BSD version by ssh’ing over to the BSD machine, doing `emacs —batch` and 
then connecting to it via `emacsclient -n -c -e nil -u`.  I end up with a macOS 
Emacs and a Free BSD Emacs being displayed on my laptop.

I’ve been playing with frames, displays, and monitors and I more or less 
understand everything I think but I think there is a bug and I have one 
question.

When I do `(display-monitor-attributes-list)` from the macOS Emacs with the 2nd 
monitor connected I get this:

```
(
 (
  (geometry 0  0 1920 1080)
  (workarea 0 25 1920 1055)
  (mm-size 478 268)
  (frames #<frame *scratch* 0x14489a030>)
  (source . "NS")
 )
 (
  (geometry 192 1080 1512 982)
  (workarea 192 1080 1512 950)
  (mm-size 301 195)
  (frames)
  (source . "NS")
 )
)
```

The top is the monitor and the bottom is the laptop’s display.  Notice that 
‘name is not present.

If I do `(display-pixel-height)` with the monitor attached, I get 2062 which is 
the sum of the two heights.  If I detach the monitor, I get 982 which is the 
height of the laptop’s display.  All good.

However, the X11 version does not do this.  I always get 2025.  The output from 
`(display-monitor-attributes-list)` changes.  With the monitor attached, there 
are two entries roughly like the one above and when the monitor is not 
attached, the output is a single entry.

The 2025 appears to be the value when the first window is opened perhaps?  It 
is the same value as the sum of the heights when the monitor is attached.  And 
it appears that it is not getting updated when the monitor is detached.  Is 
this a bug?  If so, I can report it but thought I would check here first.  (I 
also can’t follow how x_display_pixel_height works but that’s a detail.)

My question pertains to the name of the monitors.  Can I somehow give the 
monitors names that will last for the life of Emacs?

I hope my descriptions make sense to others.
Thank you for your time,
Perry

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