Confirmed in all cases it's just that the X11/Xmir apps can't detect the
session bus address of the login (which is on a different TTY BTW).
Forcing DBUS_SESSION_BUS_ADDRESS solves the problem.
Here are some stack traces of the hangs:
gedit:
(gdb) bt
#0 0x7705e853 in select () at ../sysdeps/unix/syscall-template.S:84
#1 0x7477acd1 in g_spawn_sync ()
from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2 0x7477b313 in g_spawn_command_line_sync ()
from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3 0x77862b70 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#4 0x778645f2 in g_dbus_address_get_for_bus_sync ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#5 0x7786f7ee in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#6 0x7787522b in g_bus_get_sync ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#7 0x7784b969 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#8 0x778488f3 in g_application_register ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#9 0x7784918f in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#10 0x778494f2 in g_application_run ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#11 0x00400cfa in main ()
nautilus:
(gdb) bt
#0 0x734c9833 in __select_nocancel ()
at ../sysdeps/unix/syscall-template.S:84
#1 0x7418ecd1 in g_spawn_sync ()
from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2 0x7418f313 in g_spawn_command_line_sync ()
from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3 0x74729b70 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#4 0x7472b5f2 in g_dbus_address_get_for_bus_sync ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#5 0x747367ee in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#6 0x7473c22b in g_bus_get_sync ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#7 0x74712969 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#8 0x7470f8f3 in g_application_register ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#9 0x0042c78e in ?? ()
#10 0x7fffedd29e40 in ffi_call_unix64 ()
from /usr/lib/x86_64-linux-gnu/libffi.so.6
#11 0x7fffedd298ab in ffi_call ()
from /usr/lib/x86_64-linux-gnu/libffi.so.6
#12 0x7441fcf5 in g_cclosure_marshal_generic_va ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#13 0x7441f1d4 in ?? ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#14 0x744394b8 in g_signal_emit_valist ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#15 0x7443a08f in g_signal_emit ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#16 0x74710168 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#17 0x747104f2 in g_application_run ()
from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#18 0x0042ba31 in ?? ()
#19 0x733ed7e0 in __libc_start_main (main=0x42b970, argc=1,
argv=0x7fffe5b8, init=, fini=,
rtld_fini=, stack_end=0x7fffe5a8)
at ../csu/libc-start.c:291
#20 0x0042ba99 in ?? ()
/usr/games/sol:
(gdb) bt
#0 0x7537556d in read () at ../sysdeps/unix/syscall-template.S:84
#1 0x70fdacf8 in _dbus_read ()
from /lib/x86_64-linux-gnu/libdbus-1.so.3
#2 0x70fde349 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#3 0x70fd2c95 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#4 0x70fd2b3a in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#5 0x70fbd32f in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#6 0x70fb8e08 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#7 0x7fffedc925f6 in atspi_get_a11y_bus ()
from /usr/lib/x86_64-linux-gnu/libatspi.so.0
#8 0x739e9052 in atk_bridge_adaptor_init ()
from /usr/lib/x86_64-linux-gnu/libatk-bridge-2.0.so.0
#9 0x77117134 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#10 0x75f3dfa5 in g_closure_invoke ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#11 0x75f4ffc1 in ?? ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#12 0x75f58d5c in g_signal_emit_valist ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#13 0x75f5908f in g_signal_emit ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#14 0x75f424d4 in ?? ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#15 0x75f44961 in g_object_notify ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#16 0x76de5778 in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#17 0x75f3e1d4 in ?? ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#18 0x75f589a6 in g_signal_emit_valist ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#19 0x75f59555 in g_signal_emit_by_name ()
from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#20 0x76e0b6c5 in ?? () from
