HTML dropdown options hidden when Qt.WindowStaysOnTopHint - Regression 5.13.1 -> 5.14.1

We're seeing this issue on macOS Catalina and Windows 10. We only have these environments for reproducing the bug; we don't suggest the bug is limited to these environments.

Using `Qt.WindowStaysOnTopHint` causes HTML select drop downs to no longer render. Omitting the window flag causes the select to render as normal.

I've reproduced the issue using the `Qt5.14.1/Examples/Qt-5.14.1/webengine/minimal/` project. The full project is attached as are video examples of the issue.

Any workarounds ahead of a 5.14.x revision are very appreciated. This bug has blindsided us a bit.

Thank you very much!