User-Agent: Mozilla/5.0 (X11; U; Linux i686; de; rv:1.8) Gecko/20060110 Firefox/1.5 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; de; rv:1.8) Gecko/20060110 Firefox/1.5 Installation of spell check dictionary "extensions" requires write permissions on the program folder. Not every user might have these privileges - especially on Linux. Reproducible: Always Steps to Reproduce: 1. Download spell checker "extension", eg. http://downloads.mozdev.org/dictionaries/spell-de-DE.xpi 2. In Thunderbird, go to Extensions window and install that "extension" Actual Results: If a user has no write permission to the program folder, the installation silently fails. Expected Results: Installation succeeds and a new spelling dictionary is available. Normal extensions can be easily installed using the Extensions window. That's so, because normal extensions are installed in the profile folder which is in the $HOME or %AppData% directories, where the user of course HAS write permission. Since the dictionary is also installed using the Extensions manager, I assumed that they were installed in the profile as well. Especially, since there was no indication stating otherwise. And finally, the installation of a spell checker is a user thing. Not every user on a system might need all the spell checkers from other users on the same system. Marking this "Major", as it makes it impossible for normal Linux (and in theory also Windows) users to install a dictionary.

Forgot to mention - that bug report is about Thunderbird 1.5.

dupe of bug 216382, but see also bug 267390 *** This bug has been marked as a duplicate of 216382 ***