Starting chromium as default browser in thunderbird

Thunderbird seems to always start firefox when a link is clicked. This is bad behaviour.

The following command will start chromium:

gconftool-2 --type string -s /desktop/gnome/url-handlers/http/command "/usr/bin/chromium %s"

This works also in KDE

other solution: jan 2012

Nothing helped, so I've found other solution:
1) in Thunderbird go to Edit -> Preferences -> Advanced -> General ->  Configuration Edito
2) change
network.protocol-handler.warn-external.http and 
network.protocol-handler.warn-external.https
to "true"
3)Click on any link in tb
4) navigate to /usr/bin/google-chrome
5) have fun