how to allow 12-digit code Rated 5 out of 5 stars
To fix "only 8-digit code" bug, in Vista, go to (it should look something like that):
C:\Users\YourUser\AppData\Roaming\Mozilla\Firefox\Profiles\abrakadabra.default\extensions\firstname.lastname@example.org\chrome\content and open "options.xul" file with Notepad or something similar to it. And Replace all 8's to 12's.
Don't know about XP, but this file (options.xul) should be somewhere there too (try to use search).