On Mon, 31 Jul 2023 at 20:57:25 +0200, Michał Byrecki wrote:
> > (org.gnome.Nautilus:51577): GLib-GObject-WARNING **: 20:53:04.844:
> > invalid cast from 'GdkWaylandToplevel' to 'GdkX11Surface'
> >
> > (org.gnome.Nautilus:51577): GLib-GObject-WARNING **: 20:53:04.844:
> > invalid cast from 'GdkWaylandDisplay' to 'GdkX11Display'
These warnings indicate that a component is assuming that all windows
are X11 windows, and all displays are X11 displays; and that's also the
cause of the segfault, while calling XGetWindowAttributes on something
that is not a valid X11 window (probably a null pointer dereference).
> > #1 0x00007ffff070d467 in () at /usr/lib/x86_64-linux-gnu/gtk-4.0/4.0.0/immodules/libim-scim.so
This component seems to be the one that is making that assumption.
The bug affects multiple GTK 4 apps because it's a module that has been
loaded into GTK 4.
Looking at scim-gtk-immodule's GTK 4 code in
<https://github.com/scim-im/scim/commit/d35bf5d331d885e94914fea6eab9c56f20666c8d>,
it does things like this:
> #ifdef GDK_WINDOWING_X11
> GdkX11Display *display = NULL;
>
> if (widget != NULL) {
> display = GDK_X11_DISPLAY (gtk_widget_get_display(widget));
> } else {
> display = GDK_X11_DISPLAY (gdk_display_get_default ());
> }
That's not correct code: just because the X11 windowing system is
compiled into GTK, that doesn't mean it is the one currently in use. The
GdkDisplay object might be a GdkX11Display, but equally it might be a
GdkWaylandDisplay. (That's why GDK_BACKEND=x11 is a workaround for this,
because when that environment variable is set, the X11 windowing system
*is* the one in use.)
I haven't checked what scim-gtk-immodule does for GTK 3, but if it has the
same pattern there, it would be equally problematic for GTK 3.
The correct pattern is more like this:
GdkDisplay *display;
if (widget != NULL) {
display = gtk_widget_get_display (widget));
} else {
display = gdk_display_get_default ();
}
#ifdef GDK_WINDOWING_X11
if (GDK_IS_X11_DISPLAY (display) {
GdkX11Display *x11_display = GDK_X11_DISPLAY (display);
/* ... do X11 things with x11_display ... */
}
#endif
#ifdef GDK_WINDOWING_WAYLAND
if (GDK_IS_WAYLAND_DISPLAY (display) {
GdkWaylandDisplay *wayland_display = GDK_WAYLAND_DISPLAY (display);
/* ... do Wayland things with wayland_display ... */
}
#endif
Until scim-gtk-immodule is fixed, the workaround would be to either set
GDK_BACKEND=x11, or use an X11 desktop environment or a desktop environment
in X11 mode (like the "GNOME (Xorg)" option for GNOME), or remove
scim-gtk-immodule and use a different input method framework such as ibus.
Forwarding comments from https://bugs.debian.org/1042759#37 :