i am pretty sure that after FF 15 you need to use tiddlyfox the only other option is to edit your prefs.js file to include your TW file as a trusted source. i believe that there is a drawback or two associated with this such as an entry needed for each TW that you use or are ever going to use.
you can check out this thread for more info: https://groups.google.com/forum/?fromgroups=#!topic/tiddlywikidev/1Em8cJviVKk -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To view this discussion on the web visit https://groups.google.com/d/msg/tiddlywiki/-/CMsdM1Na9O4J. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/tiddlywiki?hl=en.

