import QtQuick 2.12
import QtQuick.Controls 2.12
import QtQuick.Window 2.12

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

    Window {
        id: window

        Rectangle {
            anchors.fill: parent
            color: "red"
        }
    }

    Button {
        text: "Open"
        onClicked: {
            window.width += 50;
            window.height += 50;
            window.show();
        }
    }
}