Using Qt 5.5.1, WebEngine from today's Git and 47-based Chromium. When I call winId() on some widget, WebEngine becomes black. Quick and dirty sample project is attached. Steps to reproduce:
1) compile and run:
$ qmake && make
$ ./webeng3 file://$PWD/w.html
2) Enter some URL in the appeared window
The application will load the specified URL into the WebEngine widget, then call winId() on the plugin. After calling winId(), WebEngine becomes completely black.