Change default email template in Thunderbird

Opensuse 11.2 x86-64
KDE 3.2.1
Thunderbird 3.0b4

Thunderbird doesn’t offer a way to make a user created email template the default when “create new message” is selected. Instead, one must open the templates folder and open one’s template directly. A minor annoyance, but frequent. Surely there are files with code defining both the default and my preferred template; I would like to try substituting the code for my template in place of that for the plain vanilla Thunderbird default, but can’t seem to find the files I would need. Can anyone point me in the general direction?

I use a workaround:

I make a template (in my case an HTML template) and store that file somewhere. I link that as a signature file (even though it’s not a signature, it’s a full template). Then I get a full template appearing automatically when I start a new email.

Occasionally I don’t want to use a template, so I use CTRL+a to select it all – and hit delete to make it disappear.

I also don’t want a template when I reply to other emails so: I set in the account settings to not use the signature if I’m replying to another person’s email because in my case I only want to use a template for initial outgoing mail, not for backwards and forwards replies.

I simply saved the template as an html file, and used that as the signature. Works fine. Thank you.