indicator-applet does not show Preferred Applications

[harmscon]

Binary package hint: indicator-applet

I use Mozilla Thunderbird for email. After installing ThunderBird via the Ubuntu Software Center and then changing my Preferred Application for Mail Reader accordingly, the indicator-applet only offers me to check Evolution Mail. I would expect it to respect my choice and offer to open my preferred application.

Karmic Koala: i686, desktop
All karmic updates have been applied to date.
ii indicator-appl 0.2.0-0ubuntu2 GNOME panel indicator applet

ProblemType: Bug
Architecture: i386
Date: Wed Oct 21 15:22:22 2009
DistroRelease: Ubuntu 9.10
Package: indicator-applet 0.2.0-0ubuntu2
ProcEnviron:
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
SourcePackage: indicator-applet
Uname: Linux 2.6.31-14-generic i686
XsessionErrors:
 (gnome-settings-daemon:1431): GLib-CRITICAL **: g_propagate_error: assertion `src != NULL' failed
 (gnome-settings-daemon:1431): GLib-CRITICAL **: g_propagate_error: assertion `src != NULL' failed
 (nautilus:1465): Eel-CRITICAL **: eel_preferences_get_boolean: assertion `preferences_is_initialized ()' failed
 (polkit-gnome-authentication-agent-1:1478): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
 (yelp:10144): Yelp-WARNING **: Failed to load config file: No such file or directory

[harmscon (harmscon)]

Just to clarify 'indicator-applet': I'm referring to the back-of-an-envelope icon on the Gnome panel next to the time and date.

Left click gives the options for sending and receiving messages via Empathy and sending and receiving email via Evolution.
Right click gives About (from where I got the package name: indicator-applet), Remove from Panel and Lock to Panel.