https://bugs.winehq.org/show_bug.cgi?id=47104
--- Comment #11 from Gabriel Ivăncescu gabrielopcode@gmail.com --- Ok, I've updated the patch in the original bug report, it now works around vst-bridge as well (the same workaround also works on full-screen apps, so it's a bit safer anyway).
I think it's a good idea to keep this workaround so people can still use vst-bridge for now, at least until we find a way to reparent it properly.
Note that the reparenting is already buggy. For example with Synth1 VST, turning knobs is bugged and the mouse snaps to the position Wine thinks it is at (i.e. near top-left). Clicking, however, works fine. This happens even in vanilla Wine so it has nothing to do with the staging patch, just a thing to keep in mind. The reparenting is still an issue but it already existed before to begin with.