Thanks all, sure if you find time to mess with a ui front end, by all means please do

Without knowing how hard this would be for you, I would think first iteration would be to just keep 1:1 and also not directly update defaults.list. The file format is simple csv format although i'm not keeping them in memory... i created file manually and just stream though it at run time.

Also dbus-switchboard runs as user (as it should) so it can't directly update the defaults.list. Perhaps first iteration could dump association lines to textbox for user to copy/paste? Or append commented blocks to default.list for user to uncomment and comment the existing matching line.

Feel free to pm if you want to coordinate anything.