https://bugs.winehq.org/show_bug.cgi?id=43506
--- Comment #6 from Jacob Hrbek werifGX@gmail.com --- (In reply to Jacob Hrbek from comment #5)
Relevant(?): https://docs.microsoft.com/en-us/windows/desktop/winmsg/wm-user
assuming that message alike 003f:trace:message:SPY_ExitMessage (0x20072) L"Msg" [0401] WM_USER+1 returned 00000000 003f:trace:message:SPY_EnterMessage (0x20072) L"Msg" [0401] WM_USER+1 dispatched wp=00000001 lp=006755e8
Is called in regression when the installer hangs.
Edit: also preset in winxp environment -> probably not relevant?