Some justification for this patch. After noticing SysEx data not being transmitted properly to my Roland MT-32 when going through Wine, I created a test program that confirmed that the midiOutLongMsg call on Windows is blocking. Attached are four log files generated by my test application: [win10-cb.log](/uploads/c0f6cc5c97a53988d40a516705ceacea/win10-cb.log) on Windows 10, with a notification callback function [win10-direct.log](/uploads/096c54ab6975bbfa4770118ba76e2c90/win10-direct.log) on Windows 10, without a notification callback [wine-cb.log](/uploads/33974b0ed3510c31693b7bc8848a02a5/wine-cb.log) on Wine, with a notification callback function [wine-direct.log](/uploads/540320fa4d45e73b9d52e14451f1682a/wine-direct.log) on Wine, without a notification callback -- https://gitlab.winehq.org/wine/wine/-/merge_requests/10581#note_135249