'C-x 4 4' doesn't work

[butter-radish]

other-window-prefix (C-x 4 4) isn’t programmed to work if the next command spawns a graphical window; this is sensible as most people don’t run EXWM. I was wondering if EXWM could detect when a command run with the other-window-prefix tries opening a graphical window, and spawns it in the other-window?

browse-url-firefox, which comes with Emacs, is one example of a command that always spawns graphical windows but isn’t designed to work with the other-window-prefix.

[Stebalien]

The right way to handle this is with startup notifications (https://www.freedesktop.org/wiki/Software/startup-notification/, https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#key-startupnotify, ch11ng/exwm#245).

As far as I can tell, one needs to:

1. Set DESKTOP_STARTUP_ID before invoking a command.
2. When a new window is mapped, use the startup notification protocol to figure out how it was launched.

But none of this is particularly easy.