In templates.ini, the configuration settings for
Tmpl.Title=OpenPGP for Thunderbird
do not allow the sandboxed Thunderbird/OpenPGP to make permanent changes via the
OpenPGP > Key Management
OpenPGP > Sender's Key
I think that it should be allowed.
Changes to the key ring files in the 'gnupg' folder are made by gpg.exe.
So gpg.exe needs direct access to those files, or the results end up in the sandbox folder.
Add the line:
Note: this is the default folder location for 'gnupg' on XP.
I don't know if it would be different for Vista, etc.