http://bugs.winehq.org/show_bug.cgi?id=58552
--- Comment #14 from Stian Low wineryyyyy@gmail.com --- (In reply to Patrick from comment #13)
Thank you for your efforts to bisect the issue. I just tested your latest patch (and MR 8669 from https://gitlab.winehq.org/wine/wine/-/merge_requests/8669) in a wine-tkg 10.12 build and Bitwig 5.3.12. It works in Bitwig when the VST window initially appears. But once you hide the VST window in Bitwig and make it appear again then it stops working. I'll test again with just your latest patch (so without MR 8669).
In case you use Fedora 42 x86_64 then you can find my wine build here: https://copr.fedorainfracloud.org/coprs/patrickl/wine-tkg-dev/
Thanks for testing and the links. I'm Debian 12 but Fedora ref still appreciated.
I retested opening and closing VST windows against Carla and it worked fine with the latest patch against latest commit 8fa114fae34 pulled today.
I'll try to reproduce on Bitwig (assuming the Linux version and not Windows).