secondary midi dev can't (easily) get removed
On Windows 7 64-bit:
- Set two midi output devs, and click "Ok"
- Set the 2nd midi output dev to "None" and click "Ok"
- Open the prefs again
Bug: The preferences dialog still shows the second midi output dev. Somehow it doesn't forget ancillary devs until you set all of those devs to "None" and click "Ok"