Bug 2512529

The GTK4 input-method module shipped in ibus-gtk4 (/usr/lib64/gtk-4.0/4.0.0/immodules/libim-ibus.so) enters unbounded mutual recursion with GTK when a client application creates a GtkTextView. The backtrace shows ibus_im_context_set_client_widget itself constructing a GtkTextView via g_object_new; that text view's gtk_text_view_init calls gtk_im_multicontext_set_client_widget, which delegates back into ibus_im_context_set_client_widget, which constructs another GtkTextView, and so on until stack exhaustion. The process dies with SIGSEGV (SEGV_MAPERR), with the faulting frame landing in gtk_css_static_style_get_default during CSS node init of the widget being constructed when the stack runs out.
Any GTK4 application that instantiates a GtkTextView while the ibus IM module is active crashes at startup. Observed with the ghostty terminal emulator, which crashes 100% of the time at launch. A side effect worth noting for anyone searching: when the crashing app is XFCE's configured terminal, the exo preferred-application helper reports only the misleading dialog "Failed to execute default Terminal Emulator. Input/output error."

Reproducible: Always

Steps to Reproduce:
1. XFCE X11 session on rawhide with the default imsettings configuration (GTK_IM_MODULE=ibus)
2. Run ghostty from a shell
3. Process segfaults before mapping a window
Actual Results:
SIGSEGV, core dumped, within about a second of launch.


Expected Results:
Terminal window opens.


Additional Information:
Regression window: first crash on this machine 2026-08-05, immediately after the 2026-08-04 update transaction that installed ibus-1.5.35~alpha2-5.fc45 and gtk4-4.23.2-2.fc45 together.

Workaround: launching with GTK_IM_MODULE=gtk-im-context-simple avoids the ibus module and the application starts normally.

Backtrace (coredumpctl gdb, with gtk4-4.23.3-1.fc45; frames 11-19 repeat as 20-28 and onward, one full cycle per GtkTextView constructed):
#0  0x00007f002fd0c51f in gtk_css_static_style_get_default () from /lib64/libgtk-4.so.1
#1  0x00007f002fced503 in gtk_css_node_init () from /lib64/libgtk-4.so.1
#2  0x00007f003020a443 in g_type_create_instance () from /lib64/libgobject-2.0.so.0
#3  0x00007f00301ef344 in g_object_new_internal.part () from /lib64/libgobject-2.0.so.0
#4  0x00007f00301f0ad7 in g_object_new_with_properties () from /lib64/libgobject-2.0.so.0
#5  0x00007f00301f1ad1 in g_object_new () from /lib64/libgobject-2.0.so.0
#6  0x00007f002fc7d102 in gtk_widget_init () from /lib64/libgtk-4.so.1
#7  0x00007f003020a443 in g_type_create_instance () from /lib64/libgobject-2.0.so.0
#8  0x00007f00301ef344 in g_object_new_internal.part () from /lib64/libgobject-2.0.so.0
#9  0x00007f00301f0ad7 in g_object_new_with_properties () from /lib64/libgobject-2.0.so.0
#10 0x00007f00301f1ad1 in g_object_new () from /lib64/libgobject-2.0.so.0
#11 0x00007f002c392449 in ibus_im_context_set_client_widget () from /usr/lib64/gtk-4.0/4.0.0/immodules/libim-ibus.so
#12 0x00007f002fb5f087 in gtk_im_multicontext_set_delegate () from /lib64/libgtk-4.so.1
#13 0x00007f002fb63dbd in gtk_im_multicontext_get_delegate () from /lib64/libgtk-4.so.1
#14 0x00007f002fb63eb3 in gtk_im_multicontext_set_client_widget () from /lib64/libgtk-4.so.1
#15 0x00007f002fc5dcb7 in gtk_text_view_init () from /lib64/libgtk-4.so.1
#16 0x00007f003020a488 in g_type_create_instance () from /lib64/libgobject-2.0.so.0
#17 0x00007f00301ef344 in g_object_new_internal.part () from /lib64/libgobject-2.0.so.0
#18 0x00007f00301f0ad7 in g_object_new_with_properties () from /lib64/libgobject-2.0.so.0
#19 0x00007f00301f1ad1 in g_object_new () from /lib64/libgobject-2.0.so.0
#20 0x00007f002c392449 in ibus_im_context_set_client_widget () from /usr/lib64/gtk-4.0/4.0.0/immodules/libim-ibus.so
#21 0x00007f002fb5f087 in gtk_im_multicontext_set_delegate () from /lib64/libgtk-4.so.1
#22 0x00007f002fb63dbd in gtk_im_multicontext_get_delegate () from /lib64/libgtk-4.so.1
#23 0x00007f002fb63eb3 in gtk_im_multicontext_set_client_widget () from /lib64/libgtk-4.so.1
#24 0x00007f002fc5dcb7 in gtk_text_view_init () from /lib64/libgtk-4.so.1