This is gone from Qt6.
used in https://invent.kde.org/frameworks/plasma-framework/-/blob/master/src/plasmaquick/dialog.cpp#L731 and https://invent.kde.org/plasma/plasma-workspace/-/blob/master/shell/panelview.cpp#L817
https://invent.kde.org/frameworks/plasma-framework/-/merge_requests/452 addresses the first one.