QML Settings not saved when using window close button

[solarisx]

Hi

I use Qt.labs.settings 1.1 (QT 5.13.2) in my QML app. They work fine if I close the app by calling Qt.quit() in qml. If I close the app by clicking the "window close button" on the Windows window frame, the settings are not saved. Is this because of the window frame is in c++?
How to fix this?

Greets