MIDI Channels unmute when changing files, but player does not show this

[zefie]

Anyone who has messed with MIDI channels then changed files knows of this bug.

To reproduce:

1. Open a midi and play it
2. mute at least one channel
3. load another file
4. channels are unmuted but boxes are still unchecked as if they were muted

I haven't decided the approach to fix this:

1. The player could just re-check the boxes when a new file is loaded
2. The player could re-mute the channels when a new file is loaded

If you have a preferred solution please comment below.