Qt 5.6: Flash content cannot enter full screen on QWebEngineView
The flash player can not enter full screen mode. I am testing it with www.haibian.com where I watch a video and click on the full screen button (bottom right). I get nothing, the button is invalid.
PS. I load the Pepper as my flash plugin.
It is a known limitation. Pepper Flash for some odd reason use a completely separate fullscreen system than the rest of Blink or Chromium, and it integrates badly with QtWebEngine.
If you have control over content, one thing you could probably do, is use HTML5 fullscreen mode to set the embed or object element fullscreen, instead of using the Flash fullscreen.