Suggestion: No native application

[anonderpling]

I think this technically should be possible with a userchrome.js script, since I believe these have full access to browser functions. I'm not sure if they're able to export functions to regular addons, however they're certainly able to modify the toolbar to add menus. The functions for listing(?) and launching can be found in aboutProfiles.js. Regardless of this, they can certainly run native applications, so if provided the location of firefox.exe (or possibly given that the system install is in the path), it can run Firefox -P $profilename)