no transparent or semi transparent widget background (on android)

I have tried in several ways to give a widget a semi-transparent background in android. Unfortunately I only got to the success via a workaround. With these variants I have tried to create a semi transparent background:

Flags:

• WA_TranslucentBackground is used to give the widget a alpha channel
• WindowFlag Qt::FramelessWindowHint needed in every version for windows otherwise there is no WA_TranslucentBackground used

• version 1 - semit transparent background in stylesheet
  -> windows: popup background is transparent
  -> android: popup background is black
• version 2 - semit transparent background in stylesheet - without WA_TranslucentBackground flag (widget has no alpha channed)
  -> windows: popup background is green without any transparency
  -> android: popup background is green without any transparency
• version 3 - set palette (like in: https://bugreports.qt.io/browse/QTBUG-43635)
  -> windows: popup background is transparent
  -> android: popup background is black
• version 4 - set palette (like in: https://bugreports.qt.io/browse/QTBUG-43635) - without WA_TranslucentBackground flag (widget has no alpha channed)
  -> windows: popup background is green without any transparency
  -> android: popup background is green without any transparency
• version 5 - use paint event and WA_TranslucentBackground
  -> windows: popup background is semi transparent green hurray
  -> android: popup background is green without any transparency
• version 6 - use paint event and WA_TranslucentBackground and a empty QQuickWidget in mainWindow
  -> windows: popup background is semi transparent green hurray
  -> android: popup background is semi transparent green hurray

So as you can see I can only generate a semi transparent background on android if I use a QQuickWidget in the mainWindow.

I would happy if someone can have a look into this issue and tell us how we can create such widgets without a QuickWidget inside the parent.

I attached the reproducible project with all variations from above - just uncomment the version you want to see.