My xinitrc file says that I should notify you about a crash in the panel.I could not find a good copy for editing purposes so I will reproduce a small part of my file here. 
panel=`which xfce4-panel`
case "x$panel" in
        x|xno*)
               ;;
        *)
               $panel
               ret=$?
               while test $ret -ne 0; do
                       xmessage -center -file - -timeout 20 -title Error <<EOF
A crash occured in the panel
Please report this to the xfce4-dev@xfce.org list
or on http://bugs.xfce.org
Meanwhile the panel will be restarted
EOF 
                        cat >&2 <<EOF
A crash occured in the panel
Please report this to the xfce4-dev@xfce.org list
or on http://bugs.xfce.org
Meanwhile the panel will be restarted
EOF
                        $panel 
                        ret=$?
                done
                ;;
esac

if test $kill_sshagent -eq 1; then
        eval `$sshagent -k`
fi
xsetroot -bg white -fg red -solid black -cursor_name watch

This is the very last line of the file.
This code appears in another file called xinitrc.xfce. Both are in my xinit
folder in etc/X11. My xinit folder also contains xinit.twm. I first noticed this
in my .xinitrc file in my home folder while viewing it in midnight commander.
My operating system is vectorlinux-5.8. I have a Compaq Deskpro EN Pentium III
computer operating at 733 MHz with an 815 chipset.