Window item lacks "focus" property and Keys attached property

The QtQuick.Window item doesn't seem to get keyboard focus.

Code like the following:

import QtQuick.Window 2.0

Window {
    Keys.onReturnPressed: console.log("Return was pressed")
}

will not emit warnings when run, yet does nothing when the Return key is pressed. Also, it's not possible to specify "focus: true", because that causes a parser error.