QML Drawer lockup when attached to top edge which does not coincide with screen top edge

import QtQuick 2.11
import QtQuick.Window 2.11
import QtQuick.Controls 2.4

ApplicationWindow {
    id: applicationWindow
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    header: Rectangle {
        color: "red"

        // Make my height 0 and no lockup.
        height: 40
    }

    Button {
        anchors.centerIn: parent
        text: "Toggle Drawer"
        onClicked: drawer.opened ? drawer.close() : drawer.open()
    }

    Drawer {
        id: drawer
        width: applicationWindow.width
        height: 0.2 * applicationWindow.height

        // Parenting to something not full screen height seems to break TopEdge mode.
        parent: applicationWindow.contentItem

        // Change me to left or right and no lockup.
        edge: Qt.TopEdge

        Label {
            anchors.centerIn: parent
            text: "a drawer"
        }
    }
}