Replace qt window embed in a widget via QWidget::createWindowContainer

Question

I have a QML window embed inside a QWidget via QWidget::createWindowContainer().

To provide some reloading capabilities without hiding the window, I would like to be able to replace the underlying (embed) qml window, without destroying and recreating the parent widget.

What I tried so far is

QQmlApplicationEngine engine;

// First time
// Load the qml file
engine.load("main.qml");
// Get the window
QWindow* window = static_cast<QWindow*>(engine.rootObjects().last());
// Create the window container
QWidget* container = QWidget::createWindowContainer(qmlWindow);
// -> This works perfectly well

// Other times
// Get the old window
QWindow* oldWindow = static_cast<QWindow*>(engine.rootObjects().last());
// And its container
QWindow* container = oldWindow->parent();
// Close the old window
lOldWindow->close();

// Load the qml
engine.load("main.qml");
// Get the new qml window
QWindow* window = static_cast<QWindow*>(engine.rootObjects().last());
// Reparent it to the old window's container
lWindow->setParent(lContainer);
// -> The newly created window does not show up

I used to completely delete the container window and recreate it as well (with createWindowContainer) and this was working perfectly well, but I would like to avoid deleting the container widget over and over. How can I achieve this ?

(Please note there is no pointer checking nor error handling for code simplicity, there is no need to comment about that :) )