Yeah, count me in. I'm one of the early adopters who can no longer call firefox from thunderbird now that 3.0 is installed. (I'm running firefox 3.5.5, also). I've been using update-notifier to stay up to date since last month (it bugs me about every four hours), so I'm reasonably well updated.
Thunderbird calls a script /usr/lib/thunderbird-3.0/openbrowers.sh and attempts to read the preferred browser from the gconf settings.
Forgive me for being a literalist: isn't the name of the script
open-browser.sh as opposed to
openbrowsers.sh?
If you want, you can edit the script and just add exec firefox after the #Exit with Error Message.
# Exit with Error Message
exec firefox
I've done this, still no luck.
or you can copy and paste in a terminal console.
gconftool-2 -s /desktop/gnome/url-handlers/http/command '/usr/bin/firefox %s' --type String
gconftool-2 -s /desktop/gnome/url-handlers/https/command '/usr/bin/firefox %s' --type String
If you will, please break this down a bit. Are we running these lines as commands from a root console, or adding them to the open-browser.sh script? I'm not at all familiar with gconftool (maybe I should learn a bit about it? I'm a KDE man, myself, and this looks kinda like a GNOME tool.)
I'm still having trouble with this, and this isn't the first time I've seen a problem like this between firefox and thunderbird - none of the other solutions I've tried in the past has worked (editing about:config, editing user.js, didn't find /etc/thunderbird.conf and didn't want to just create one yet...) If it's any consolation, editing the preferences in firefox's about:config page did restore the mailto functionality so firefox will call thunderbird, it just doesn't work the other way around yet.
Eh. I'll putter around and see what I'm missing, and check back here later.