Focus scope does not handle disabling active item

import QtQuick 2.2
import QtQuick.Layouts 1.1

Rectangle {
    width: 800
    height: 480

    Keys.onPressed: {
        event.accepted = true;
        switch(event.key)
        {
        case Qt.Key_1:
            box1.enabled = !box1.enabled;
            return;
        case Qt.Key_2:
            box2.enabled = !box2.enabled;
            return;
        case Qt.Key_3:
            box3.enabled = !box3.enabled;
            return;
        case Qt.Key_4:
            box4.enabled = !box4.enabled;
            return;
        }
        event.accepted = false;
    }

    Text {
        anchors.centerIn: parent
        width: 300
        height: 480
        horizontalAlignment: Text.AlignLeft
        verticalAlignment: Text.AlignVCenter
        wrapMode: Text.Wrap
        text:
"Use cursor keys to move focus around.

Active focus is indicated with green.
Focus indicated with red border.
Disabled is indicated with grey.

Use keys 1,2,3,4 to toggle the enabled property on the left boxes.

Try having active focus on box1, then disable it. It becomes inpossible to use the up/down cursor keys to move to the next items in that column. You can use the right cursor to move to the right column, but if you move back, you still cannot reach the other boxes on the left.

Also try having focus on box1, then go right. Disable box 1, and try to go back left. Active focus will go only to the focus scope behind the buttons.
"
    }

    Rectangle {
        anchors.fill: leftColumn
        color: leftColumn.activeFocus ? "green" : "transparent"
        border.color: "red"
        border.width: leftColumn.focus ? 2 : 0
    }

    FocusScope {
        id: leftColumn
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.bottom: parent.bottom
        width: 200
        focus: true

        ColumnLayout {

            anchors.fill: parent
            Rectangle {
                focus: true
                id: box1
                color: enabled ? (activeFocus ? "green" : "orange") : (activeFocus ? "blue" : "gray")
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "box1"
                }
                KeyNavigation.down: box2
                KeyNavigation.right: rightColumn
                activeFocusOnTab: true
            }

            Rectangle {
                focus: true
                id: box2
                color: enabled ? (activeFocus ? "green" : "orange") : (activeFocus ? "blue" : "gray")
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "box2"
                }
                KeyNavigation.down: box3
                KeyNavigation.right: rightColumn
                activeFocusOnTab: true
            }

            Rectangle {
                focus: true
                id: box3
                color: enabled ? (activeFocus ? "green" : "orange") : (activeFocus ? "blue" : "gray")
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "box3"
                }
                KeyNavigation.down: box4
                KeyNavigation.right: rightColumn
                activeFocusOnTab: true
            }

            Rectangle {
                focus: true
                id: box4
                color: enabled ? (activeFocus ? "green" : "orange") : (activeFocus ? "blue" : "gray")
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "box4"
                }
                KeyNavigation.down: box1
                KeyNavigation.right: rbox1
                activeFocusOnTab: true
            }
        }
    }

    Rectangle {
        anchors.fill: rightColumn
        color: rightColumn.activeFocus ? "green" : "transparent"
        border.color: "red"
        border.width: rightColumn.focus ? 2 : 0
    }

    FocusScope {
        id: rightColumn
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.bottom: parent.bottom
        width: 200
        ColumnLayout {
            anchors.fill: parent

            Rectangle {
                focus: true
                id: rbox1
                color: enabled ? (activeFocus ? "green" : "orange") : "gray"
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "rightbox1"
                }
                KeyNavigation.down: rbox2
                KeyNavigation.left: leftColumn
                activeFocusOnTab: true
            }
            Rectangle {
                focus: true
                id: rbox2
                color: enabled ? (activeFocus ? "green" : "orange") : "gray"
                border.color: "red"
                border.width: focus ? 2 : 0
                width: 180
                height: 30
                Text {
                    anchors.fill: parent
                    text: "rightbox2"
                }
                KeyNavigation.down: rbox1
                KeyNavigation.left: leftColumn
                activeFocusOnTab: true
            }
        }
    }
}