thunderbird / preferred web browser

[Dennis J.]

Hi,
How does one configure a custom preferred web browser that opens when 
clicking on a link in an email in thunderbird?
I installed a trunk build of Firefox in /opt/firefox but when I specify 
"/opt/firefox/firefox -P exp" as a preferred application then I only get a 
new window with the default mozilla homepage and not the url i clicked on.
I also called a shell-script that dumps $* into a logfile which ends up 
empty so I wonder how that URL is passed to the called app if not as a 
parameter?

Regards,
   Dennis