FWIW I can confirm the crash, and got this GDB backtrace and Valgrind log:
<details><summary>GDB backtrace for the crash (nothing new though)</summary>
```gdb Thread 1 "geany" received signal SIGSEGV, Segmentation fault. 0x00007fffeefb2f51 in ibus_input_context_reset () from /lib/x86_64-linux-gnu/libibus-1.0.so.5 (gdb) bt #0 0x00007fffeefb2f51 in ibus_input_context_reset () at /lib/x86_64-linux-gnu/libibus-1.0.so.5 #1 0x00007ffff408edc2 in () at /usr/lib/x86_64-linux-gnu/gtk-3.0/3.0.0/immodules/im-ibus.so #6 0x00007ffff769ddbf in <emit signal ??? on instance 0x555556ae1920 [ScintillaObject]> (instance=instance@entry=0x555556ae1920, signal_id=<optimized out>, detail=detail@entry=0) at ../../../gobject/gsignal.c:3606 #2 0x00007ffff6e90bc7 in _gtk_marshal_BOOLEAN__BOXED (closure=0x555556b229a0, return_value=0x7fffffffd660, n_param_values=<optimized out>, param_values=0x7fffffffd6c0, invocation_hint=<optimized out>, marshal_data=<optimized out>) at gtk/gtkmarshalers.c:84 #3 0x00007ffff76843b0 in g_closure_invoke (closure=0x555556b229a0, return_value=return_value@entry=0x7fffffffd660, n_param_values=2, param_values=param_values@entry=0x7fffffffd6c0, invocation_hint=invocation_hint@entry=0x7fffffffd640) at ../../../gobject/gclosure.c:832 #4 0x00007ffff7697076 in signal_emit_unlocked_R (node=<optimized out>, detail=detail@entry=0, instance=instance@entry=0x555556ae1920, emission_return=emission_return@entry=0x7fffffffd7b0, instance_and_params=instance_and_params@entry=0x7fffffffd6c0) at ../../../gobject/gsignal.c:3796 #5 0x00007ffff769d42d in g_signal_emit_valist (instance=<optimized out>, signal_id=<optimized out>, detail=<optimized out>, var_args=var_args@entry=0x7fffffffd860) at ../../../gobject/gsignal.c:3559 #7 0x00007ffff7169844 in gtk_widget_event_internal (widget=widget@entry=0x555556ae1920 [ScintillaObject], event=event@entry=0x555556ad59e0) at ../../../gtk/gtkwidget.c:7812 #8 0x00007ffff716c481 in gtk_widget_event_internal (event=0x555556ad59e0, widget=0x555556ae1920 [ScintillaObject]) at ../../../gtk/gtkwidget.c:7383 #9 0x00007ffff700783e in propagate_event_up (topmost=<optimized out>, event=<optimized out>, widget=0x555556ae1920 [ScintillaObject]) at ../../../gtk/gtkmain.c:2598 #10 propagate_event (widget=widget@entry=0x555556ae1920 [ScintillaObject], event=event@entry=0x555556ad59e0, captured=captured@entry=0, topmost=topmost@entry=0x0) at ../../../gtk/gtkmain.c:2701 #11 0x00007ffff7008b7c in gtk_propagate_event (widget=widget@entry=0x555556ae1920 [ScintillaObject], event=event@entry=0x555556ad59e0) at ../../../gtk/gtkmain.c:2735 #12 0x00007ffff70092f6 in gtk_main_do_event (event=0x555556ad59e0) at ../../../gtk/gtkmain.c:1921 #13 gtk_main_do_event (event=<optimized out>) at ../../../gtk/gtkmain.c:1691 #14 0x00007ffff7ec6815 in _gdk_event_emit (event=event@entry=0x555556ad59e0) at ../../../gdk/gdkevents.c:73 #15 0x00007ffff7f207a2 in gdk_event_source_dispatch (source=<optimized out>, callback=<optimized out>, user_data=<optimized out>) at ../../../gdk/x11/gdkeventsource.c:367 #16 0x00007ffff6b3e7a9 in g_main_dispatch (context=0x555555630ba0) at ../../../glib/gmain.c:3454 #17 g_main_context_dispatch (context=context@entry=0x555555630ba0) at ../../../glib/gmain.c:4172 #18 0x00007ffff6b3ea38 in g_main_context_iterate (context=0x555555630ba0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../glib/gmain.c:4248 #19 0x00007ffff6b3ecef in g_main_loop_run (loop=loop@entry=0x5555566c7470) at ../../../glib/gmain.c:4448 #20 0x00007ffff7008495 in gtk_main () at ../../../gtk/gtkmain.c:1329 #21 0x00007ffff7a9cf1e in main_lib (argc=<optimized out>, argv=<optimized out>) at ../../src/libmain.c:1260 #22 0x0000555555555142 in main (argc=<optimized out>, argv=<optimized out>) at ../../src/main.c:27 ``` </details>
<details><summary>Memcheck report for the crash:</summary>
```valgrind memcheck ==3332905== Invalid read of size 8 ==3332905== at 0xB697DA6: ??? (in /usr/lib/x86_64-linux-gnu/gtk-3.0/3.0.0/immodules/im-ibus.so) ==3332905== by 0x4ED2BC6: _gtk_marshal_BOOLEAN__BOXED (gtkmarshalers.c:84) ==3332905== by 0x5B5A3AF: g_closure_invoke (gclosure.c:832) ==3332905== by 0x5B6D075: signal_emit_unlocked_R.isra.0 (gsignal.c:3796) ==3332905== by 0x5B7342C: g_signal_emit_valist (gsignal.c:3559) ==3332905== by 0x5B73DBE: g_signal_emit (gsignal.c:3606) ==3332905== by 0x51AB843: gtk_widget_event_internal.part.0 (gtkwidget.c:7812) ==3332905== by 0x504983D: propagate_event_up (gtkmain.c:2598) ==3332905== by 0x504983D: propagate_event (gtkmain.c:2701) ==3332905== by 0x504B2F5: gtk_main_do_event (gtkmain.c:1921) ==3332905== by 0x504B2F5: gtk_main_do_event (gtkmain.c:1691) ==3332905== by 0x569F814: _gdk_event_emit (gdkevents.c:73) ==3332905== by 0x56F97A1: gdk_event_source_dispatch (gdkeventsource.c:367) ==3332905== by 0x5BFD7A8: g_main_dispatch (gmain.c:3454) ==3332905== by 0x5BFD7A8: g_main_context_dispatch (gmain.c:4172) ==3332905== Address 0x315ff7e8 is 72 bytes inside a block of size 176 free'd ==3332905== at 0x484317B: free (vg_replace_malloc.c:872) ==3332905== by 0x5B7C213: g_type_free_instance (gtype.c:2003) ==3332905== by 0x5BF9A28: g_source_callback_unref (gmain.c:1739) ==3332905== by 0x5BF9A28: g_source_callback_unref (gmain.c:1732) ==3332905== by 0x5BF9F0E: g_source_destroy_internal (gmain.c:1404) ==3332905== by 0x5BFD70F: g_main_dispatch (gmain.c:3484) ==3332905== by 0x5BFD70F: g_main_context_dispatch (gmain.c:4172) ==3332905== by 0x5BFDA37: g_main_context_iterate.constprop.0 (gmain.c:4248) ==3332905== by 0x5BFDCEE: g_main_loop_run (gmain.c:4448) ==3332905== by 0x504A494: gtk_main (gtkmain.c:1329) ==3332905== by 0x48EDF1D: main_lib (libmain.c:1260) ==3332905== by 0x109141: main (main.c:27) ==3332905== Block was alloc'd at ==3332905== at 0x48407B4: malloc (vg_replace_malloc.c:381) ==3332905== by 0x5C03678: g_malloc (gmem.c:130) ==3332905== by 0x5C1C011: g_slice_alloc (gslice.c:1074) ==3332905== by 0x5C1C648: g_slice_alloc0 (gslice.c:1100) ==3332905== by 0x5B7BE8C: g_type_create_instance (gtype.c:1903) ==3332905== by 0x5B5FD2F: g_object_new_internal (gobject.c:2228) ==3332905== by 0x5B613FB: g_object_new_with_properties (gobject.c:2391) ==3332905== by 0x5B62000: g_object_new (gobject.c:2037) ==3332905== by 0xB699591: ibus_im_context_new (in /usr/lib/x86_64-linux-gnu/gtk-3.0/3.0.0/immodules/im-ibus.so) ==3332905== by 0x5027241: _gtk_im_module_create (gtkimmodule.c:656) ==3332905== by 0x5027EBB: gtk_im_multicontext_get_slave (gtkimmulticontext.c:281) ==3332905== by 0x502840D: gtk_im_multicontext_set_client_window (gtkimmulticontext.c:331) ==3332905== ``` </details>
I however have for now no clue what the issue is or even where (is it Scintilla doing something problematic with multiple concurrent views, is it a timing bug in IBus or GTK?).