https://bugs.winehq.org/show_bug.cgi?id=39440
--- Comment #1 from phant0m anton.kalmykov@gmail.com --- Created attachment 52556 --> https://bugs.winehq.org/attachment.cgi?id=52556 Simple code to demonstrate the bug
I've created a simple program, which can help to catch this issue (see it in the attachments). You can build it via simple "make" command and run the "embedder" binary. Ideally, you should see the white square (embedded window) on the black background. But all window will be black. The child embedded window isn't visible without my patch.