Hi,
with 0.4.0 tomboy crashes often when opening the context menu or the preferences when running as panel applet:

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================

Stacktrace:

  at (wrapper managed-to-native) _Gnome.PanelAppletFactory.panel_applet_factory_main (intptr,intptr,_GnomeSharp.PanelAppletFactoryCallbackNative,intptr) <0x00004>
  at (wrapper managed-to-native) _Gnome.PanelAppletFactory.panel_applet_factory_main (intptr,intptr,_GnomeSharp.PanelAppletFactoryCallbackNative,intptr) <0xffffffff>
  at _Gnome.PanelAppletFactory.Register (System.Type) <0x00158>
  at Tomboy.Tomboy.RegisterPanelAppletFactory () <0x0000c>
  at Tomboy.Tomboy.Main (string[]) <0x000c5>
  at (wrapper runtime-invoke) System.Object.runtime_invoke_void_string[] (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

        mono(mono_handle_native_sigsegv+0xde) [0x81565ee]
        mono [0x8122e28]
        [0xffffe440]
        /usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b) [0xb6a8e83b]
        /usr/lib/libbonobo-2.so.0(bonobo_closure_invoke_va_list+0x254) [0xb6615d84]
        /usr/lib/libbonobo-2.so.0(bonobo_closure_invoke+0x19e) [0xb6615f9e]
        /usr/lib/libbonoboui-2.so.0 [0xb67d4e2a]
        /usr/lib/libbonobo-2.so.0(_ORBIT_skel_small_Bonobo_UIComponent_execVerb+0x21) [0xb6618161]
        /usr/lib/libORBit-2.so.0(ORBit_c_stub_invoke+0x120) [0xb6526cd0]
        /usr/lib/libbonobo-2.so.0(Bonobo_UIComponent_execVerb+0x74) [0xb661fa44]
        /usr/lib/libbonoboui-2.so.0 [0xb67db81b]
        /usr/lib/libgobject-2.0.so.0(g_cclosure_marshal_VOID__POINTER+0x59) [0xb6a9b199]
        /usr/lib/libgobject-2.0.so.0 [0xb6a8d059]
        /usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b) [0xb6a8e83b]
        /usr/lib/libgobject-2.0.so.0 [0xb6a9f293]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x8c7) [0xb6aa0167]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29) [0xb6aa0329]
        /usr/lib/libbonoboui-2.so.0(bonobo_ui_engine_emit_verb_on_w+0x58) [0xb67d7388]
        /usr/lib/libbonoboui-2.so.0 [0xb67e0a05]
        /usr/lib/libgobject-2.0.so.0(g_cclosure_marshal_VOID__VOID+0x49) [0xb6a9bbd9]
        /usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b) [0xb6a8e83b]
        /usr/lib/libgobject-2.0.so.0 [0xb6a9ec43]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x8c7) [0xb6aa0167]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29) [0xb6aa0329]
        /usr/lib/libgtk-x11-2.0.so.0(gtk_widget_activate+0x94) [0xb6ed1f94]
        /usr/lib/libgtk-x11-2.0.so.0(gtk_menu_shell_activate_item+0x118) [0xb6dc7458]
        /usr/lib/libgtk-x11-2.0.so.0 [0xb6dc8a22]
        /usr/lib/libgtk-x11-2.0.so.0 [0xb6dc0615]
        /usr/lib/libgtk-x11-2.0.so.0(_gtk_marshal_BOOLEAN__BOXED+0x60) [0xb6dba780]
        /usr/lib/libgobject-2.0.so.0 [0xb6a8d059]
        /usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b) [0xb6a8e83b]
        /usr/lib/libgobject-2.0.so.0 [0xb6a9f293]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x68f) [0xb6a9ff2f]
        /usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29) [0xb6aa0329]
        /usr/lib/libgtk-x11-2.0.so.0 [0xb6ecdbf8]
        /usr/lib/libgtk-x11-2.0.so.0(gtk_propagate_event+0x183) [0xb6db3b73]
        /usr/lib/libgtk-x11-2.0.so.0(gtk_main_do_event+0x317) [0xb6db4d77]
        /usr/lib/libgdk-x11-2.0.so.0 [0xb6c2787a]
        /usr/lib/libglib-2.0.so.0(g_main_context_dispatch+0x182) [0xb7e64872]
        /usr/lib/libglib-2.0.so.0 [0xb7e6784f]
        /usr/lib/libglib-2.0.so.0(g_main_loop_run+0x1a9) [0xb7e67bf9]
        /usr/lib/libbonobo-2.so.0(bonobo_main+0x63) [0xb6603a23]
        /usr/lib/libbonobo-2.so.0(bonobo_generic_factory_main_timeout+0xd9) [0xb6601c89]
        /usr/lib/libbonobo-2.so.0(bonobo_generic_factory_main+0x33) [0xb6601d13]
        /usr/lib/libpanel-applet-2.so.0(panel_applet_factory_main_closure+0xd1) [0xb61bcad1]
        /usr/lib/libpanel-applet-2.so.0(panel_applet_factory_main+0x55) [0xb61bcbb5]
        [0xb5eb6cab]
        [0xb5eb5a99]
        [0xb5eb58f5]
        [0xb7940986]
        [0xb79407c3]
        mono(mono_runtime_exec_main+0x62) [0x80996f2]
        mono(mono_runtime_run_main+0x1b9) [0x80999d9]
        mono(mono_main+0xe47) [0x805d4b7]
        mono [0x805c162]
        /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xdc) [0xb7cc18cc]
        mono [0x805c0b1]
Abandon (core dumped)

Bye

Ubuntu Bug: https://launchpad.net/distros/ubuntu/+source/tomboy/+bug/59057