"'App' is not responding" dialog is stealing all keyboard input
[Originally filed as a Fedora 40 issue at https://bugzilla.redhat.com/show_bug.cgi?id=2292205 "''App' is not respoding' dialog is stealing all keyboard input", where it asked me to redirect here:]
[I /assume/ the issue is Mutter behavior. Please redirect if that assumption is wrong.]
When one app is not responding and its window is overlaid with the "'App' is not responding" dialog, it appears that all keyboard input is stolen by that dialog: Trying to do keyboard input into another window that has focus has no effect, and esp. typing the return key causes that (non-focused) "'App' is not responding" dialog's pre-selected "Force Quit" to be executed unexpectedly.
Reproducible: Always
mutter-46.2-2.fc40.x86_64, running the standard GNOME/Wayland environment