The FreeDesktop notification spec defines some optional hints that notification servers can support, two of which are "sound-file" and "sound-name", both of which are intended to play a notification sound.

After a bit of testing, it seems like mako doesn't support these hints. I tried notify-send "Sound test!" -h STRING:sound-file:/sound/file/path with an MP3 file and a WAV file, and neither played a sound.

I also tested playing sound names with sounds that are installed on my PC: notify-send "Sound test" -h STRING:sound-name:bell, also without success.

Ideally, all applications that display notifications should use the Desktop Notifications Specification, and ideally they should not play any sound of their own, but instead provide a sound file path or sound name to the notification server. This enables features such as "busy mode" on the notification server to pause notifications, or overriding notification sounds. If the application plays its own audio then a "busy mode" feature would be almost pointless.

But currently, if an application relies on the notification server to play sounds, the notification sound would not play when using Mako. (Unless I misunderstood something.)

Bonus, if Mako added support for "sound-file" and "sound-name", then it would probably be trivial to add a configuration option to set a default value for these hints, in case applications don't provide one. That would solve #36 in a very nice way.