No settings change from 27 where all was fine. plugin.disable_full_page_plugin_for_types still contains "application/pdf,audio/x-mpeg,audio/mpeg", the media.windows-media-foundation.enabled is still set to "false", and the mime types are all set to "ask". Is there a reason why these settings are being ignored in FF 28? Major pain in the neck to have to save something and then run it in VLC as opposed to just being asked from FF as I was until 15 minutes ago when I restarted FF and the upgrade happened.

I also just tried this with a pdf and it opened in the current tab. When I set FF to "ask" about pdfs instead of "preview in Firefox" I got the dialog asking what I wanted to do. Since the plugin.disable_full_page_plugin_for_types already included "application/pdf" I don't know if it should have previewed in FF as I don't know how the different settings interact, but to be honest I'm okay with that behaviour. It's the mp3 starting to play in a new tab (or, rather, attempting to play as I have Flashblock installed which stops this) that really bothers me.