void Application::registerQmlTypes()
{
    qmlRegisterType<CanvasPaneItem>("App", 1, 0, "CanvasPaneItem");
    qmlRegisterType<ImageCanvas>();
    qmlRegisterType<ImageCanvas>("App", 1, 0, "ImageCanvas");
    qmlRegisterUncreatableType<CanvasPane>("App", 1, 0, "CanvasPane", "Can't create instances of CanvasPane");

    qRegisterMetaType<CanvasPane*>();
    qRegisterMetaType<CanvasPaneItem*>();
    qRegisterMetaType<ImageCanvas*>();
}

import QtQuick 2.13
import QtQuick.Controls 2.13

import App 1.0

ApplicationWindow {
    id: window
    width: 1200
    height: 800

    CanvasPaneItem {
        id: paneItem
        pane: canvas.paneAt(0)
//        pane: theCanvas.paneAt(0)
        anchors.fill: parent
    }
}