https://bugs.winehq.org/show_bug.cgi?id=57225
--- Comment #1 from RĂ©mi Bernon rbernon@codeweavers.com --- Is https://github.com/iXit/wine-nine-standalone the thing to use to reproduce this?
Fwiw it seems to be using winex11 private DC ExtEscape codes for its own purposes, I've dropped one of them in dec9f8780e61ff7c536ac08a0433e8734ce1f3ca, but the general behavior may have changed.
I'll have a look but IMO we cannot guarantee that this they will be there, or keep their semantics forever, it would create too much friction on how Wine presents its windows.