Description of problem:
Abrt found a crash of mate-panel.

How reproducible:
I haven't tried to reproduce it yet.

Steps to reproduce:
1. Boot a system which has got two user accounts.
2. Log in with the first one.
3. Use the "switch user" functionality, in order to keep the first session open.
4. Log in with the second user account.

Actual results:
1. abrt notifies about this crash

Expected results:
1. Ideally, no crashes should occur, even though this doesn't look so serious, since the system seems to work properly.

Additional info:
qemu-kvm guest, installed from "Fedora-MATE_Compiz-Live-x86_64-24-20160531.n.0.iso" ISO.

Version-Release number of selected component:
mate-panel-1.14.0-2.fc24

Additional info:
reporter:       libreport-2.7.1
backtrace_rating: 4
cmdline:        mate-panel
crash_function: g_type_check_instance_is_fundamentally_a
executable:     /usr/bin/mate-panel
global_pid:     1617
kernel:         4.5.5-300.fc24.x86_64
pkg_fingerprint: 73BD E983 81B4 6521
pkg_vendor:     Fedora Project
reproducible:   Not sure how to reproduce the problem
runlevel:       unknown
type:           CCpp
uid:            1001

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 g_type_check_instance_is_fundamentally_a at gtype.c:4031
 #2 container_child_background_set at panel-applet-frame-dbus.c:239
 #3 g_simple_async_result_complete at gsimpleasyncresult.c:801
 #4 set_applet_property_cb at panel-applet-container.c:560
 #5 g_task_return_now at gtask.c:1107
 #6 g_task_return at gtask.c:1165
 #7 g_dbus_connection_call_done at gdbusconnection.c:5702
 #8 g_task_return_now at gtask.c:1107
 #9 complete_in_idle_cb at gtask.c:1121
 #14 gtk_main at gtkmain.c:1268

Potential duplicate: bug 1238820