Avidemux from Flathub, an X11 app. I guess we might need to stub something related to the parenting mechanism for portal dialogs to X11 windows?
#0 wl_proxy_get_version (proxy=proxy@entry=0x0) at ../src/wayland-client.c:2313
#1 0x00005622a34e0ba4 in mutter_x11_interop_set_x11_parent (mutter_x11_interop=0x0, surface=0x5622abadf390, xwindow=23068678) at src/mutter-x11-interop-client-protocol.h:92
#2 set_x11_parent (external_window=<optimized out>) at ../src/externalwindow-wayland.c:124
#3 0x00007f14eaf0c64a in g_closure_invoke (closure=0x5622abd11eb0, return_value=0x0, n_param_values=2, param_values=0x7ffc6d9bc1c0, invocation_hint=0x7ffc6d9bc110) at ../gobject/gclosure.c:834
#4 0x00007f14eaf3c5f3 in signal_emit_unlocked_R.isra.0 (node=node@entry=0x7ffc6d9bc2c0, detail=detail@entry=2105, instance=instance@entry=0x5622abade900, emission_return=emission_return@entry=0x0, instance_and_params=instance_and_params@entry=0x7ffc6d9bc1c0) at ../gobject/gsignal.c:3888
#5 0x00007f14eaf2d104 in signal_emit_valist_unlocked (instance=instance@entry=0x5622abade900, signal_id=signal_id@entry=1, detail=detail@entry=2105, var_args=var_args@entry=0x7ffc6d9bc430) at ../gobject/gsignal.c:3520
#6 0x00007f14eaf2d361 in g_signal_emit_valist (instance=0x5622abade900, signal_id=1, detail=2105, var_args=var_args@entry=0x7ffc6d9bc430) at ../gobject/gsignal.c:3263
#7 0x00007f14eaf2d423 in g_signal_emit (instance=<optimized out>, signal_id=<optimized out>, detail=<optimized out>) at ../gobject/gsignal.c:3583
#8 0x00007f14eaf187b4 in g_object_dispatch_properties_changed (object=0x5622abade900, n_pspecs=<optimized out>, pspecs=<optimized out>) at ../gobject/gobject.c:1819
#9 0x00007f14eaf1ef8a in g_object_notify_by_spec_internal (object=0x5622abade900, pspec=<optimized out>) at ../gobject/gobject.c:1924
#10 g_object_notify (object=0x5622abade900, property_name=0x7f14ea972f3b "mapped") at ../gobject/gobject.c:1974
#11 g_object_notify (object=0x5622abade900, property_name=0x7f14ea972f3b "mapped") at ../gobject/gobject.c:1951
#12 0x00007f14ea7f2e40 in maybe_notify_mapped (surface=0x5622abade900) at ../gdk/wayland/gdkdragsurface-wayland.c:135
#13 gdk_wayland_surface_configure (surface=0x5622abade900) at ../gdk/wayland/gdksurface-wayland.c:959
#14 0x00007f14e9992056 in ffi_call_unix64 () at ../src/x86/unix64.S:104
#15 0x00007f14e998e6a0 in ffi_call_int (cif=cif@entry=0x7ffc6d9bc750, fn=<optimized out>, rvalue=<optimized out>, avalue=<optimized out>, closure=closure@entry=0x0) at ../src/x86/ffi64.c:673
#16 0x00007f14e99914ee in ffi_call (cif=cif@entry=0x7ffc6d9bc750, fn=<optimized out>, rvalue=rvalue@entry=0x0, avalue=avalue@entry=0x7ffc6d9bc820) at ../src/x86/ffi64.c:710
#17 0x00007f14e9f2b10e in wl_closure_invoke (closure=closure@entry=0x5622abd6e050, target=<optimized out>, target@entry=0x5622abd36c40, opcode=opcode@entry=0, data=<optimized out>, flags=1) at ../src/connection.c:1228
#18 0x00007f14e9f2b979 in dispatch_event (display=display@entry=0x5622aa749790, queue=queue@entry=0x5622abadf350) at ../src/wayland-client.c:1670
#19 0x00007f14e9f2bd73 in dispatch_queue (display=0x5622aa749790, queue=0x5622abadf350) at ../src/wayland-client.c:1816
#20 wl_display_dispatch_queue_pending (display=0x5622aa749790, queue=0x5622abadf350) at ../src/wayland-client.c:2058
#21 0x00007f14ea7de780 in _gdk_wayland_display_queue_events (display=0x5622aa74fd00) at ../gdk/wayland/gdkeventsource.c:229
#22 0x00007f14ea82d13b in gdk_display_get_event (display=0x5622aa74fd00) at ../gdk/gdkdisplay.c:533
#23 0x00007f14ea7e4876 in gdk_event_source_dispatch (base=<optimized out>, callback=<optimized out>, data=<optimized out>) at ../gdk/wayland/gdkeventsource.c:138
#24 0x00007f14eb185e8c in g_main_dispatch (context=0x5622aa73bab0) at ../glib/gmain.c:3344
#25 g_main_context_dispatch_unlocked (context=0x5622aa73bab0) at ../glib/gmain.c:4152
#26 0x00007f14eb1e7c98 in g_main_context_iterate_unlocked.isra.0 (context=0x5622aa73bab0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4217
#27 0x00007f14eb18bf37 in g_main_loop_run (loop=0x5622aa7a0550) at ../glib/gmain.c:4419
#28 0x00005622a34ac8dc in main (argc=<optimized out>, argv=<optimized out>) at ../src/xdg-desktop-portal-gnome.c:336
Avidemux from Flathub, an X11 app. I guess we might need to stub something related to the parenting mechanism for portal dialogs to X11 windows?