https://bugs.winehq.org/show_bug.cgi?id=44827
--- Comment #2 from ajduck@outlook.com --- Still happening as of Wine 3.19 and a distro upgrade (a clean install) from elementary OS 0.4 Loki (based on Ubuntu 16.04) to elementary OS 5.0 Juno (based on Ubuntu 18.04).
Weirdly after doing this clean install, the soft lock when launching FL 20 that I described in the previous comment isn't happening anymore. (Might be to do with the new 18.04 base?)
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Link to more recent version of FL: http://demodownload.image-line.com/flstudio/flstudio_win_20.0.5.681.exe
$ sha1sum flstudio_win_20.0.5.681.exe 11901b66a65c526203dacbab7ec6a3c61edb1553 flstudio_win_20.0.5.681.exe