Default viewer?

I can no longer choose my default page source viewer. Even in about:config, I can choose my view_source.editor.path and set the view_source.editor.external to true but I still get FF as the ONLY page source viewer. I want my Notepad++ back! GRRRR!!! I'm with an earlier poster - I would migrate to Chrome but for some deal busters there (FF is sneaking up on it, though).