Here is the backtrace :

nelson@nelson-desktop:~$ gdb avant-window-navigator
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu"...
(gdb) run
Starting program: /usr/bin/avant-window-navigator
[Thread debugging using libthread_db enabled]
[New Thread 0x7f0c2d4b97a0 (LWP 6567)]
Screen is composited.
LOADED : /usr/share/applications/firefox.desktop
LOADED : /usr/share/applications/pidgin.desktop
LOADED : /usr/share/applications/totem.desktop
LOADED : /usr/share/applications/ooo-writer.desktop
LOADED : /usr/share/applications/banshee-1.desktop
LOADED : /usr/share/applications/amule.desktop
LOADED : /usr/share/applications/gnome-terminal.desktop
APPLET : /usr/lib/awn/applets/taskman.desktop
APPLET : /usr/share/avant-window-navigator/applets/showdesktop.desktop
APPLET : /usr/share/avant-window-navigator/applets/shinyswitcher.desktop
WM=compiz
ShinySwitcher Message:  compiz detected
ShinySwitcher Message:  viewport/compiz detected.. using existing workspace
config
cols = 1,  rows=1
AwnTask: drag_data_received_handl
 Receiving string: file:///usr/share/applications/gimp.desktop
Desktop file: /usr/share/applications/gimp.desktop
LOADED : file:///usr/share/applications/gimp.desktop

Launched application : 6582
Remove : /usr/share/applications/gimp.desktop

(avant-window-navigator:6567): GLib-GObject-WARNING **: instance of invalid
non-instantiatable type `<invalid>'

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f0c2d4b97a0 (LWP 6567)]
_task_wnck_state_changed (window=<value optimized out>,
    old=<value optimized out>, new=<value optimized out>, task=0xec40c0)
    at awn-task.c:1015
1015    awn-task.c: No such file or directory.
    in awn-task.c
(gdb) bt
#0  _task_wnck_state_changed (window=<value optimized out>,
    old=<value optimized out>, new=<value optimized out>, task=0xec40c0)
    at awn-task.c:1015
#1  0x00007f0c2bafebcf in IA__g_closure_invoke (closure=0x15c8e70,
    return_value=0x0, n_param_values=3, param_values=0x7fff354ef270,
    invocation_hint=0x7fff354ef150)
    at /build/buildd/glib2.0-2.16.4/gobject/gclosure.c:490
#2  0x00007f0c2bb127f8 in signal_emit_unlocked_R (node=0x14f4770, detail=0,
    instance=0x189c2e0, emission_return=0x0,
    instance_and_params=0x7fff354ef270)
    at /build/buildd/glib2.0-2.16.4/gobject/gsignal.c:2440
#3  0x00007f0c2bb14255 in IA__g_signal_emit_valist (instance=0x189c2e0,
    signal_id=<value optimized out>, detail=0, var_args=0x7fff354ef4f0)
    at /build/buildd/glib2.0-2.16.4/gobject/gsignal.c:2199
#4  0x00007f0c2bb14643 in IA__g_signal_emit (instance=0x2, signal_id=0,
    detail=32) at /build/buildd/glib2.0-2.16.4/gobject/gsignal.c:2243
#5  0x00007f0c2d0b913a in ?? () from /usr/lib/libwnck-1.so.22
#6  0x00007f0c2d0b9f5a in ?? () from /usr/lib/libwnck-1.so.22
#7  0x00007f0c2b4623d4 in IA__g_main_context_dispatch (context=0x659280)
    at /build/buildd/glib2.0-2.16.4/glib/gmain.c:2012
#8  0x00007f0c2b4656e5 in g_main_context_iterate (context=0x659280, block=1,

    dispatch=1, self=<value optimized out>)
    at /build/buildd/glib2.0-2.16.4/glib/gmain.c:2645
---Type <return> to continue, or q <return> to quit---
#9  0x00007f0c2b465a05 in IA__g_main_loop_run (loop=0x7f5de0)
    at /build/buildd/glib2.0-2.16.4/glib/gmain.c:2853
#10 0x00007f0c2cc0af03 in IA__gtk_main ()
    at /build/buildd/gtk+2.0-2.12.9/gtk/gtkmain.c:1163
#11 0x0000000000408a77 in main (argc=1, argv=0x7fff354ef9d8) at main.c:347

I hope this will be fixed soon. AWN Rox :) even if there is a lot of
additional functionalities that i wish see on it, i keep it as the best OS X
like dock.

Cordially, Nelson H.