Emacs-as-compositor deadlocks on GTK dialog boxes

When Emacs is itself the Wayland compositor (e.g. EWM in module mode), a y-or-n-p/yes-or-no-p reached from a mouse event (menu item, button) with use-dialog-box non-nil opens a GTK dialog and blocks in GTK's modal loop; the dialog is a toplevel that needs Emacs Lisp to place it, so the session deadlocks. Symptoms: pointer moves and other clients still get input, but Emacs never redraws, emacsclient --eval times out, SIGUSR2 does nothing, and the main thread sleeps in poll() with no child process to blame. Fix: (setopt use-dialog-box nil use-file-dialog nil). Recovery needs a debugger with sudo (ptrace_scope=1) or a restart; save open apps from /proc first (terminal cwd plus foreground command).