External MIDI + Roland SC-88VL Sound Canvas + Hanging notes

[Onkel Hotte]

I just got myself an external Roland SC-88VL connected over USB-Midi. I tried Space Quest 3 with external midi as output device, and decided to close scummvm during the intro to try another game. Looks like the currently played notes stay on because they don't receive a note-off.
Would it be possible to send an "all notes off" midi message when the application quits?