Comment 2 for bug 1548006

StacktraceTop:
 _gdk_window_has_impl (window=window@entry=0x0) at /build/gtk+3.0-hryEEv/gtk+3.0-3.18.7/./gdk/gdkwindow.c:626
 gdk_x11_window_get_xid (window=0x0) at /build/gtk+3.0-hryEEv/gtk+3.0-3.18.7/./gdk/x11/gdkwindow-x11.c:5527
 gtk_im_context_xim_filter_keypress (context=0x2b38260, event=0x32d4120) at /build/gtk+3.0-hryEEv/gtk+3.0-3.18.7/./modules/input/gtkimcontextxim.c:673
 gtk_im_multicontext_filter_keypress (context=0x7ffacc0b4870, event=0x32d4120) at /build/gtk+3.0-hryEEv/gtk+3.0-3.18.7/./gtk/gtkimmulticontext.c:359
 st_im_text_captured_event () from /tmp/apport_sandbox_IwvrJ3/usr/lib/gnome-shell/libgnome-shell.so