I get a segfault on every Gtk+ program I try to run using the broadway backend.
Gtk+ version is latest master from git. Running on ArchLinux latest with
xserver 1.10, the gnome3 packages from archlinux extras and gtk+ master.

The guys over bugs.gnome.org redirected my bug here (original report https://bugzilla.gnome.org//show_bug.cgi?id=649170)

Program segfaults in gtk+/gdk/x11/gdkproperty-x11.c:242

g_return_val_if_fail (ATOM_TO_INDEX (atom) < virtual_atom_array->len, None);

(gdb) p virtual_atom_array 
$5 = (GPtrArray *) 0x0

-----------------------
GDK_BACKEND=broadway gnome-calculator


(gcalctool:23829): GLib-GObject-WARNING **: invalid cast from
`GdkBroadwayDisplay' to `GdkX11Display'

Backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff752ecc8 in gdk_x11_atom_to_xatom_for_display (display=0x6a4020,
atom=0x6bc) at gdkproperty-x11.c:242

#0  0x00007ffff752ecc8 in gdk_x11_atom_to_xatom_for_display (display=0x6a4020, atom=0x6bc) at gdkproperty-x11.c:242
#1  gdk_x11_atom_to_xatom_for_display (display=0x6a4020, atom=0x6bc) at gdkproperty-x11.c:223
#2  0x00007ffff0db793d in ?? () from /usr/lib/gtk-3.0/modules/libcanberra-gtk-module.so
#3  0x00007ffff74f8f9f in gdk_threads_dispatch (data=<value optimized out>) at gdk.c:754