Description of problem:
Fairly regularly, xfce4-panel will segfaults during a vnc server startup.  It
can be started afterwards without problem.  Not sure if this is really a
xfce4-panel issue or a library issue, but here goes.  Stack trace (may or may
not be valid):

Version-Release number of selected component (if applicable):
#0  0x0000003f2ea3ac58 in IA__g_ascii_strcasecmp (s1=0x4165d6 "xfce",
    s2=0x21 <Address 0x21 out of bounds>) at gstrfuncs.c:1753
#1  0x00000000004116d6 in notify_cb (
    name=0x220000002e <Address 0x220000002e out of bounds>,
channel_name=Variable "channel_name" is not available.
)
    at mcs_client.c:109
#2  0x0000003ae3302bf6 in read_settings (client=0x5e3370, channel_name=Variable
"channel_name" is not available.
)
    at mcs-client.c:250
#3  0x0000003ae3303132 in mcs_client_process_event (client=Variable "client" is
not available.
) at mcs-client.c:792
#4  0x0000000000411747 in client_event_filter (xevent=Variable "xevent" is not
available.
) at mcs_client.c:129
#5  0x0000003a06d3d326 in gdk_event_apply_filters (xevent=0x7fffffd86850,
    event=0x6ecc00, filters=Variable "filters" is not available.
) at gdkevents-x11.c:328
#6  0x0000003a06d3e8bc in gdk_event_translate (display=0x537b30, event=0x6ecc00,
    xevent=0x7fffffd86850, return_exposes=0) at gdkevents-x11.c:872
#7  0x0000003a06d40078 in _gdk_events_queue (display=0x537b30) at
gdkevents-x11.c:2193
#8  0x0000003a06d400df in gdk_event_dispatch (source=Variable "source" is not
available.
) at gdkevents-x11.c:2253
#9  0x0000003f2ea24a9e in IA__g_main_context_dispatch (context=0x546c80) at
gmain.c:1934
#10 0x0000003f2ea27734 in g_main_context_iterate (context=0x546c80, block=1,
    dispatch=1, self=Variable "self" is not available.
) at gmain.c:2565
#11 0x0000003f2ea27c20 in IA__g_main_loop_run (loop=0x6f89f0) at gmain.c:2769
#12 0x0000003a06802145 in IA__gtk_main () at gtkmain.c:1009
#13 0x00000000004113d2 in main (argc=1, argv=0x7fffffd86cd8) at main.c:501
(gdb) up
#1  0x00000000004116d6 in notify_cb (
    name=0x220000002e <Address 0x220000002e out of bounds>,
channel_name=Variable "channel_name" is not available.
)
    at mcs_client.c:109
109         if (g_ascii_strcasecmp (CHANNEL, channel_name))
(gdb) list
104     /* event handling */
105     static void
106     notify_cb (const char *name, const char *channel_name,
107                McsAction action, McsSetting * setting, void *data)
108     {
109         if (g_ascii_strcasecmp (CHANNEL, channel_name))
110             return;
111
112         switch (action)
113         {


How reproducible:
Fairly.

Steps to Reproduce:
1. startup vncserver with the following xstartup:

#!/bin/sh

ulimit -c unlimited

if [ -f $HOME/.Xresources ]
then
   xrdb $HOME/.Xresources
fi
xsetroot -solid grey
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#mwm
xfwm4 &
xfce4-panel &