Areo Snap not Working for Qml + FramelessWindowHint on Windows

Hey,

when using the FramelessWindowHint flag on a Qt Application Window, Windows' Areo Snap functionality stops working.

On Windows 10:

• Windows + Arrow Keys do not work
• Snap after startSystemMove() does not work
• Dropshadow missing

On Linux (GNOME + Mutter WM + X)

• Windows + Arrow Keys work
• Snap after startSystemMove() works
• Dropshadow there

On Linux (GNOME + Mutter WM + Wayland)

• Windows + Arrow Keys work
• Snap after startSystemMove() works
• Dropshadow missing

Please find a minimal working example in Python: https://github.com/trin94/framelesswindow-arrow-keys-windows

I've also added a screen recording on Windows and a recording on Linux (X server).

Please also see QTBUG-84466