The following QML file has the following parse error

import QtQuick 2.0 as QtQuick
import QtQuick.Window 2.0

Window {
property QtQuick.Item item: ii
QtQuick.Item

}

file:///home/alan/tmp/test2.qml:5 Unexpected token `.'
file:///home/alan/tmp/test2.qml:5 Unexpected token `identifier'

As expected, just property Item item leads to an error that Item is not a type. So there appears to be no way of using namespaced types in property declarations.