qml qt quick ui is ruined after displaying a dialog with footer or contentItem populated

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.15
import QtQuick.Layouts 1.15


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

    ColumnLayout {
        Text {
            id: x
            text: "Custom text"
            font.pixelSize: 30
        }

        Button {
            id: y
            text: "Click here!"
            font.pixelSize: 30

            MouseArea {
                onClicked: function() {
                    dialog.text = "hello world";
                    dialog.open()
                }
                anchors.fill: parent
            }
        }
    }

    Dialog {
        property string text: ""

        id: dialog
        modal:true
        focus: true
        closePolicy: Popup.CloseOnEscape
        x: Math.round((parent.width - width) / 2)
        y: Math.round((parent.height - height) / 2)

        header: Text {
            text: parent.title
        }

        footer: DialogButtonBox {
           Button {
                text: "Close"
                DialogButtonBox.buttonRole: DialogButtonBox.AcceptRole
                onClicked: dialog.accept
            }
        }
        contentItem: Text {
            text: dialog.text
        }
    }
}