Browser "share other window" doesn't work in EXWM

[WorldsEndless]

This might be part of other issues, but I don't even know where to start in seeking a solution here. Here's how it works:

With my laptop connected to an external monitor, for two screens:

1. Browser-based video meeting in EXWM (Firefox or Chrome, Zoom or Google Meet).
2. "Share Screen" -> "Select a Screen or Window": only options are browser windows or "Entire Screen"

Compare:

1. Browser-based video meeting in KDE (Firefox or Chrome, Zoom or Google Meet).
2. "Share Screen" -> "Select a Screen or Window": every window and screen are on the list

So in EXWM I can't share, e.g., just an emacs window to show my code; I have to share it all. But this isn't the case in other WMs. Can I fix this somehow?

[WJCFerguson]

(Just noting that as a very partial workaround, under the Advanced tab on Zoom you can also select an area to share)

[WorldsEndless]

Note that if I install teh Zoom app, this isn't a problem. It's my desire to use Zooom, Google Meet, or others from the browser that introduces this problem; browsers keep their scope to what it should be and just look at the properly registered windows instead of hijacking the system -- but they don't see my emacs.

[dakra]

Just want to add that this is not a fair comparison. In other window managers you also can not share only a single window in your Emacs frame. You either share the complete Emacs app or not. Same with exwm (where Emacs is simply everywhere).

In those cases I simply start a new Emacs instance inside exwm. If you put it in char-mode it works really well and you only realize you're in another Emacs inside Emacs when looking at the double modeline.

[WorldsEndless]

@dakra is completely right, about both the diagnosis and the solution. I have a blog post about this coming up: create emacs-in-emacs and use the char-mode to keep your commands straight. Downright beautiful.

[medranocalvo]

See also #723.

As @dakra comments, this is a feature that all Emacs users, EXWM or not, could use. I suggest you to report a feature request to Emacs.

[WorldsEndless]

How do I submit a feature request to emacs? All I know is `M-x report-emacs-bug` ...

[WorldsEndless]

My post regarding this solution here: https://tech.toryanderson.com/2020/10/19/emacs-in-emacs-a-triumph-for-exwm/

[medranocalvo]

@WorldsEndless, M-x report-emacs-bug is O.K., despite the name. Actually, sending an e-mail to bug-gnu-emacs@gnu.org should be enough. Let me know if you encounter difficulties, or ask in emacs-devel@gnu.org.

BTW, your posts about EXWM are great, thank you!

[medranocalvo]

Forgot to ask you to post the bug number (pref. with a link) to #723, so that we can keep track. Thank you in advance.

[quotuva]

I've been using the following for this:

(defun my/toggle-frame-present nil
  "When run in an EXWM (browser) window, split screen into 2 frames
so that the normal Emacs one (on the right) can be screen-shared
from the other. Running again toggles back."
  (interactive)
  (unless (derived-mode-p 'exwm-mode)
    (user-error "Not in EXWM window"))
  (exwm-floating-toggle-floating)
  (if exwm--floating-frame
      ;; From exwm-floating-move
      (let ((floating-container (frame-parameter exwm--floating-frame
						 'exwm-container))
	    (width (/ (display-pixel-width) 2)))
	(exwm--log "Aligning to left half")
	(exwm--set-geometry floating-container 0 0 width nil)
	(exwm--set-geometry exwm--id 0 0 width nil)
	(xcb:flush exwm--connection)
	(other-frame 1)
	(set-frame-width (selected-frame) width nil t)
	(set-frame-position (selected-frame) width 0))
    (set-frame-width (selected-frame) (display-pixel-width) nil t)
    (set-frame-position (selected-frame) 0 0)))