We could just control geometry of the c++ title bar and geometry,
but then the user wouldn't be able to style it, and users rather
style things in QML than subclassing FloatingWindow and writing C++.
So instance some .qml files to represent the drop area and floating
window, so user can muck with.
Hierarchy looks like this now:
-QQuickWindow
--FloatingWindowQuick (C++ QQuickItem)
---FloatingWindow.qml
----TitleBar.qml (reads state from TitleBar c++)
----DropArea.qml
-----DropArea (C++ QQuickItem)
------Frame
etc
