mozilla user.js

[Ross D]

Okay, a couple of minor things with Firefox and Thunderbird:

1.  When clicking a mailto: link in firefox, thunderbird opens up and
prompts for a password and such, but that's it.  It doesn't open a new
compose e-mail window, let alone automatically put the e-mail address
in the to: field.

2.  I'm not a fan of the idea that when you open up thunderbird,
someone can view your threads in your inbox (suject, sender, date,
etc.) without even typing the password.  They still can't read your
e-mail, but I'm paranoid and don't even like the idea of someone
seeing who sent me e-mails and what it's about.

After searching through some forums, it looks like the answer might
lie in each program's user.js file.  Unfortunately, I haven't figured
out where to find or create the appropriate file in Ubuntu (I tried
mozilla's general instructions for Unix systems but it didn't work). 
If anyone has any experience with these two specific problems, and/or
creating and editing a user.js file for thunderbird or firefox in
Ubuntu, could you please post what you did and how you did it?  I'm
also using Ubuntu AMD64, so please be specific to which exactly
folder, especially for the library folders.  Thanks!

Ross