The current implementation is convenient in that the parent can be either a Window or an Item (mutually exclusively):

• https://doc-snapshots.qt.io/qt6-6.7/qml-qtquick-window.html#parent-prop
• https://www.qt.io/blog/window-embedding-in-qt-quick

However, Using var seems to go against the progression towards strong typing in QML.

Suggestion: Split into something like Window.parentWindow + Window.parentItem which are strongly-typed